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Merge branch 'master' into for-2.6.35 

Conflicts:
	fs/ext3/fsync.c

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Jens Axboe 2010-05-21 21:27:26 +02:00
parent b492e95be0 d515e86e63
commit ee9a3607fb
5727 changed files with 379396 additions and 149350 deletions
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2
Documentation/00-INDEX
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@ -250,6 +250,8 @@ numastat.txt
- info on how to read Numa policy hit/miss statistics in sysfs.
oops-tracing.txt
- how to decode those nasty internal kernel error dump messages.
padata.txt
- An introduction to the "padata" parallel execution API
parisc/
- directory with info on using Linux on PA-RISC architecture.
parport.txt

31
Documentation/ABI/obsolete/sysfs-bus-usb Normal file
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@ -0,0 +1,31 @@
What: /sys/bus/usb/devices/.../power/level
Date: March 2007
KernelVersion: 2.6.21
Contact: Alan Stern <stern@rowland.harvard.edu>
Description:
Each USB device directory will contain a file named
power/level. This file holds a power-level setting for
the device, either "on" or "auto".
"on" means that the device is not allowed to autosuspend,
although normal suspends for system sleep will still
be honored. "auto" means the device will autosuspend
and autoresume in the usual manner, according to the
capabilities of its driver.
During normal use, devices should be left in the "auto"
level. The "on" level is meant for administrative uses.
If you want to suspend a device immediately but leave it
free to wake up in response to I/O requests, you should
write "0" to power/autosuspend.
Device not capable of proper suspend and resume should be
left in the "on" level. Although the USB spec requires
devices to support suspend/resume, many of them do not.
In fact so many don't that by default, the USB core
initializes all non-hub devices in the "on" level. Some
drivers may change this setting when they are bound.
This file is deprecated and will be removed after 2010.
Use the power/control file instead; it does exactly the
same thing.

29
Documentation/ABI/obsolete/sysfs-class-rfkill Normal file
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@ -0,0 +1,29 @@
rfkill - radio frequency (RF) connector kill switch support
For details to this subsystem look at Documentation/rfkill.txt.
What: /sys/class/rfkill/rfkill[0-9]+/state
Date: 09-Jul-2007
KernelVersion v2.6.22
Contact: linux-wireless@vger.kernel.org
Description: Current state of the transmitter.
This file is deprecated and sheduled to be removed in 2014,
because its not possible to express the 'soft and hard block'
state of the rfkill driver.
Values: A numeric value.
0: RFKILL_STATE_SOFT_BLOCKED
transmitter is turned off by software
1: RFKILL_STATE_UNBLOCKED
transmitter is (potentially) active
2: RFKILL_STATE_HARD_BLOCKED
transmitter is forced off by something outside of
the driver's control.
What: /sys/class/rfkill/rfkill[0-9]+/claim
Date: 09-Jul-2007
KernelVersion v2.6.22
Contact: linux-wireless@vger.kernel.org
Description: This file is deprecated because there no longer is a way to
claim just control over a single rfkill instance.
This file is scheduled to be removed in 2012.
Values: 0: Kernel handles events

67
Documentation/ABI/stable/sysfs-class-rfkill Normal file
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@ -0,0 +1,67 @@
rfkill - radio frequency (RF) connector kill switch support
For details to this subsystem look at Documentation/rfkill.txt.
For the deprecated /sys/class/rfkill/*/state and
/sys/class/rfkill/*/claim knobs of this interface look in
Documentation/ABI/obsolete/sysfs-class-rfkill.
What: /sys/class/rfkill
Date: 09-Jul-2007
KernelVersion: v2.6.22
Contact: linux-wireless@vger.kernel.org,
Description: The rfkill class subsystem folder.
Each registered rfkill driver is represented by an rfkillX
subfolder (X being an integer > 0).
What: /sys/class/rfkill/rfkill[0-9]+/name
Date: 09-Jul-2007
KernelVersion v2.6.22
Contact: linux-wireless@vger.kernel.org
Description: Name assigned by driver to this key (interface or driver name).
Values: arbitrary string.
What: /sys/class/rfkill/rfkill[0-9]+/type
Date: 09-Jul-2007
KernelVersion v2.6.22
Contact: linux-wireless@vger.kernel.org
Description: Driver type string ("wlan", "bluetooth", etc).
Values: See include/linux/rfkill.h.
What: /sys/class/rfkill/rfkill[0-9]+/persistent
Date: 09-Jul-2007
KernelVersion v2.6.22
Contact: linux-wireless@vger.kernel.org
Description: Whether the soft blocked state is initialised from non-volatile
storage at startup.
Values: A numeric value.
0: false
1: true
What: /sys/class/rfkill/rfkill[0-9]+/hard
Date: 12-March-2010
KernelVersion v2.6.34
Contact: linux-wireless@vger.kernel.org
Description: Current hardblock state. This file is read only.
Values: A numeric value.
0: inactive
The transmitter is (potentially) active.
1: active
The transmitter is forced off by something outside of
the driver's control.
What: /sys/class/rfkill/rfkill[0-9]+/soft
Date: 12-March-2010
KernelVersion v2.6.34
Contact: linux-wireless@vger.kernel.org
Description: Current softblock state. This file is read and write.
Values: A numeric value.
0: inactive
The transmitter is (potentially) active.
1: active
The transmitter is turned off by software.

28
Documentation/ABI/testing/sysfs-bus-usb
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@ -14,34 +14,6 @@ Description:
The autosuspend delay for newly-created devices is set to
the value of the usbcore.autosuspend module parameter.
What: /sys/bus/usb/devices/.../power/level
Date: March 2007
KernelVersion: 2.6.21
Contact: Alan Stern <stern@rowland.harvard.edu>
Description:
Each USB device directory will contain a file named
power/level. This file holds a power-level setting for
the device, either "on" or "auto".
"on" means that the device is not allowed to autosuspend,
although normal suspends for system sleep will still
be honored. "auto" means the device will autosuspend
and autoresume in the usual manner, according to the
capabilities of its driver.
During normal use, devices should be left in the "auto"
level. The "on" level is meant for administrative uses.
If you want to suspend a device immediately but leave it
free to wake up in response to I/O requests, you should
write "0" to power/autosuspend.
Device not capable of proper suspend and resume should be
left in the "on" level. Although the USB spec requires
devices to support suspend/resume, many of them do not.
In fact so many don't that by default, the USB core
initializes all non-hub devices in the "on" level. Some
drivers may change this setting when they are bound.
What: /sys/bus/usb/devices/.../power/persist
Date: May 2007
KernelVersion: 2.6.23

2
Documentation/ABI/testing/sysfs-devices-memory
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@ -43,7 +43,7 @@ Date: September 2008
Contact: Badari Pulavarty <pbadari@us.ibm.com>
Description:
The file /sys/devices/system/memory/memoryX/state
is read-write. When read, it's contents show the
is read-write. When read, its contents show the
online/offline state of the memory section. When written,
root can toggle the the online/offline state of a removable
memory section (see removable file description above)

9
Documentation/ABI/testing/sysfs-devices-platform-_UDC_-gadget Normal file
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@ -0,0 +1,9 @@
What: /sys/devices/platform/_UDC_/gadget/suspended
Date: April 2010
Contact: Fabien Chouteau <fabien.chouteau@barco.com>
Description:
Show the suspend state of an USB composite gadget.
1 -> suspended
0 -> resumed
(_UDC_ is the name of the USB Device Controller driver)

43
Documentation/ABI/testing/sysfs-driver-hid-picolcd Normal file
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@ -0,0 +1,43 @@
What: /sys/bus/usb/devices/<busnum>-<devnum>:<config num>.<interface num>/<hid-bus>:<vendor-id>:<product-id>.<num>/operation_mode
Date: March 2010
Contact: Bruno Prémont <bonbons@linux-vserver.org>
Description: Make it possible to switch the PicoLCD device between LCD
(firmware) and bootloader (flasher) operation modes.
Reading: returns list of available modes, the active mode being
enclosed in brackets ('[' and ']')
Writing: causes operation mode switch. Permitted values are
the non-active mode names listed when read.
Note: when switching mode the current PicoLCD HID device gets
disconnected and reconnects after above delay (see attribute
operation_mode_delay for its value).
What: /sys/bus/usb/devices/<busnum>-<devnum>:<config num>.<interface num>/<hid-bus>:<vendor-id>:<product-id>.<num>/operation_mode_delay
Date: April 2010
Contact: Bruno Prémont <bonbons@linux-vserver.org>
Description: Delay PicoLCD waits before restarting in new mode when
operation_mode has changed.
Reading/Writing: It is expressed in ms and permitted range is
0..30000ms.
What: /sys/bus/usb/devices/<busnum>-<devnum>:<config num>.<interface num>/<hid-bus>:<vendor-id>:<product-id>.<num>/fb_update_rate
Date: March 2010
Contact: Bruno Prémont <bonbons@linux-vserver.org>
Description: Make it possible to adjust defio refresh rate.
Reading: returns list of available refresh rates (expressed in Hz),
the active refresh rate being enclosed in brackets ('[' and ']')
Writing: accepts new refresh rate expressed in integer Hz
within permitted rates.
Note: As device can barely do 2 complete refreshes a second
it only makes sense to adjust this value if only one or two
tiles get changed and it's not appropriate to expect the application
to flush it's tiny changes explicitely at higher than default rate.

29
Documentation/ABI/testing/sysfs-driver-hid-prodikeys Normal file
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@ -0,0 +1,29 @@
What: /sys/bus/hid/drivers/prodikeys/.../channel
Date: April 2010
KernelVersion: 2.6.34
Contact: Don Prince <dhprince.devel@yahoo.co.uk>
Description:
Allows control (via software) the midi channel to which
that the pc-midi keyboard will output.midi data.
Range: 0..15
Type: Read/write
What: /sys/bus/hid/drivers/prodikeys/.../sustain
Date: April 2010
KernelVersion: 2.6.34
Contact: Don Prince <dhprince.devel@yahoo.co.uk>
Description:
Allows control (via software) the sustain duration of a
note held by the pc-midi driver.
0 means sustain mode is disabled.
Range: 0..5000 (milliseconds)
Type: Read/write
What: /sys/bus/hid/drivers/prodikeys/.../octave
Date: April 2010
KernelVersion: 2.6.34
Contact: Don Prince <dhprince.devel@yahoo.co.uk>
Description:
Controls the octave shift modifier in the pc-midi driver.
The octave can be shifted via software up/down 2 octaves.
0 means the no ocatve shift.
Range: -2..2 (minus 2 to plus 2)
Type: Read/Write

111
Documentation/ABI/testing/sysfs-driver-hid-roccat-kone Normal file
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@ -0,0 +1,111 @@
What: /sys/bus/usb/devices/<busnum>-<devnum>:<config num>.<interface num>/actual_dpi
Date: March 2010
Contact: Stefan Achatz <erazor_de@users.sourceforge.net>
Description: It is possible to switch the dpi setting of the mouse with the
press of a button.
When read, this file returns the raw number of the actual dpi
setting reported by the mouse. This number has to be further
processed to receive the real dpi value.
VALUE DPI
1 800
2 1200
3 1600
4 2000
5 2400
6 3200
This file is readonly.
What: /sys/bus/usb/devices/<busnum>-<devnum>:<config num>.<interface num>/actual_profile
Date: March 2010
Contact: Stefan Achatz <erazor_de@users.sourceforge.net>
Description: When read, this file returns the number of the actual profile.
This file is readonly.
What: /sys/bus/usb/devices/<busnum>-<devnum>:<config num>.<interface num>/firmware_version
Date: March 2010
Contact: Stefan Achatz <erazor_de@users.sourceforge.net>
Description: When read, this file returns the raw integer version number of the
firmware reported by the mouse. Using the integer value eases
further usage in other programs. To receive the real version
number the decimal point has to be shifted 2 positions to the
left. E.g. a returned value of 138 means 1.38
This file is readonly.
What: /sys/bus/usb/devices/<busnum>-<devnum>:<config num>.<interface num>/kone_driver_version
Date: March 2010
Contact: Stefan Achatz <erazor_de@users.sourceforge.net>
Description: When read, this file returns the driver version.
The format of the string is "v<major>.<minor>.<patchlevel>".
This attribute is used by the userland tools to find the sysfs-
paths of installed kone-mice and determine the capabilites of
the driver. Versions of this driver for old kernels replace
usbhid instead of generic-usb. The way to scan for this file
has been chosen to provide a consistent way for all supported
kernel versions.
This file is readonly.
What: /sys/bus/usb/devices/<busnum>-<devnum>:<config num>.<interface num>/profile[1-5]
Date: March 2010
Contact: Stefan Achatz <erazor_de@users.sourceforge.net>
Description: The mouse can store 5 profiles which can be switched by the
press of a button. A profile holds informations like button
mappings, sensitivity, the colors of the 5 leds and light
effects.
When read, these files return the respective profile. The
returned data is 975 bytes in size.
When written, this file lets one write the respective profile
data back to the mouse. The data has to be 975 bytes long.
The mouse will reject invalid data, whereas the profile number
stored in the profile doesn't need to fit the number of the
store.
What: /sys/bus/usb/devices/<busnum>-<devnum>:<config num>.<interface num>/settings
Date: March 2010
Contact: Stefan Achatz <erazor_de@users.sourceforge.net>
Description: When read, this file returns the settings stored in the mouse.
The size of the data is 36 bytes and holds information like the
startup_profile, tcu state and calibration_data.
When written, this file lets write settings back to the mouse.
The data has to be 36 bytes long. The mouse will reject invalid
data.
What: /sys/bus/usb/devices/<busnum>-<devnum>:<config num>.<interface num>/startup_profile
Date: March 2010
Contact: Stefan Achatz <erazor_de@users.sourceforge.net>
Description: The integer value of this attribute ranges from 1 to 5.
When read, this attribute returns the number of the profile
that's active when the mouse is powered on.
When written, this file sets the number of the startup profile
and the mouse activates this profile immediately.
What: /sys/bus/usb/devices/<busnum>-<devnum>:<config num>.<interface num>/tcu
Date: March 2010
Contact: Stefan Achatz <erazor_de@users.sourceforge.net>
Description: The mouse has a "Tracking Control Unit" which lets the user
calibrate the laser power to fit the mousepad surface.
When read, this file returns the current state of the TCU,
where 0 means off and 1 means on.
Writing 0 in this file will switch the TCU off.
Writing 1 in this file will start the calibration which takes
around 6 seconds to complete and activates the TCU.
What: /sys/bus/usb/devices/<busnum>-<devnum>:<config num>.<interface num>/weight
Date: March 2010
Contact: Stefan Achatz <erazor_de@users.sourceforge.net>
Description: The mouse can be equipped with one of four supplied weights
ranging from 5 to 20 grams which are recognized by the mouse
and its value can be read out. When read, this file returns the
raw value returned by the mouse which eases further processing
in other software.
The values map to the weights as follows:
VALUE WEIGHT
0 none
1 5g
2 10g
3 15g
4 20g
This file is readonly.

10
Documentation/ABI/testing/sysfs-wacom Normal file
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@ -0,0 +1,10 @@
What: /sys/class/hidraw/hidraw*/device/speed
Date: April 2010
Kernel Version: 2.6.35
Contact: linux-bluetooth@vger.kernel.org
Description:
The /sys/class/hidraw/hidraw*/device/speed file controls
reporting speed of wacom bluetooth tablet. Reading from
this file returns 1 if tablet reports in high speed mode
or 0 otherwise. Writing to this file one of these values
switches reporting speed.

2
Documentation/Changes
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@ -49,7 +49,7 @@ o oprofile 0.9 # oprofiled --version
o udev 081 # udevinfo -V
o grub 0.93 # grub --version
o mcelog 0.6
o iptables 1.4.1 # iptables -V
o iptables 1.4.2 # iptables -V
Kernel compilation

2
Documentation/DMA-API-HOWTO.txt
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@ -742,7 +742,7 @@ failure can be determined by:
Closing
This document, and the API itself, would not be in it's current
This document, and the API itself, would not be in its current
form without the feedback and suggestions from numerous individuals.
We would like to specifically mention, in no particular order, the
following people:

2
Documentation/DocBook/Makefile
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@ -14,7 +14,7 @@ DOCBOOKS := z8530book.xml mcabook.xml device-drivers.xml \
genericirq.xml s390-drivers.xml uio-howto.xml scsi.xml \
mac80211.xml debugobjects.xml sh.xml regulator.xml \
alsa-driver-api.xml writing-an-alsa-driver.xml \
tracepoint.xml media.xml
tracepoint.xml media.xml drm.xml
###
# The build process is as follows (targets):

839
Documentation/DocBook/drm.tmpl Normal file
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@ -0,0 +1,839 @@
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>
<book id="drmDevelopersGuide">
<bookinfo>
<title>Linux DRM Developer's Guide</title>
<copyright>
<year>2008-2009</year>
<holder>
Intel Corporation (Jesse Barnes &lt;jesse.barnes@intel.com&gt;)
</holder>
</copyright>
<legalnotice>
<para>
The contents of this file may be used under the terms of the GNU
General Public License version 2 (the "GPL") as distributed in
the kernel source COPYING file.
</para>
</legalnotice>
</bookinfo>
<toc></toc>
<!-- Introduction -->
<chapter id="drmIntroduction">
<title>Introduction</title>
<para>
The Linux DRM layer contains code intended to support the needs
of complex graphics devices, usually containing programmable
pipelines well suited to 3D graphics acceleration. Graphics
drivers in the kernel can make use of DRM functions to make
tasks like memory management, interrupt handling and DMA easier,
and provide a uniform interface to applications.
</para>
<para>
A note on versions: this guide covers features found in the DRM
tree, including the TTM memory manager, output configuration and
mode setting, and the new vblank internals, in addition to all
the regular features found in current kernels.
</para>
<para>
[Insert diagram of typical DRM stack here]
</para>
</chapter>
<!-- Internals -->
<chapter id="drmInternals">
<title>DRM Internals</title>
<para>
This chapter documents DRM internals relevant to driver authors
and developers working to add support for the latest features to
existing drivers.
</para>
<para>
First, we'll go over some typical driver initialization
requirements, like setting up command buffers, creating an
initial output configuration, and initializing core services.
Subsequent sections will cover core internals in more detail,
providing implementation notes and examples.
</para>
<para>
The DRM layer provides several services to graphics drivers,
many of them driven by the application interfaces it provides
through libdrm, the library that wraps most of the DRM ioctls.
These include vblank event handling, memory
management, output management, framebuffer management, command
submission &amp; fencing, suspend/resume support, and DMA
services.
</para>
<para>
The core of every DRM driver is struct drm_device. Drivers
will typically statically initialize a drm_device structure,
then pass it to drm_init() at load time.
</para>
<!-- Internals: driver init -->
<sect1>
<title>Driver initialization</title>
<para>
Before calling the DRM initialization routines, the driver must
first create and fill out a struct drm_device structure.
</para>
<programlisting>
static struct drm_driver driver = {
/* don't use mtrr's here, the Xserver or user space app should
* deal with them for intel hardware.
*/
.driver_features =
DRIVER_USE_AGP | DRIVER_REQUIRE_AGP |
DRIVER_HAVE_IRQ | DRIVER_IRQ_SHARED | DRIVER_MODESET,
.load = i915_driver_load,
.unload = i915_driver_unload,
.firstopen = i915_driver_firstopen,
.lastclose = i915_driver_lastclose,
.preclose = i915_driver_preclose,
.save = i915_save,
.restore = i915_restore,
.device_is_agp = i915_driver_device_is_agp,
.get_vblank_counter = i915_get_vblank_counter,
.enable_vblank = i915_enable_vblank,
.disable_vblank = i915_disable_vblank,
.irq_preinstall = i915_driver_irq_preinstall,
.irq_postinstall = i915_driver_irq_postinstall,
.irq_uninstall = i915_driver_irq_uninstall,
.irq_handler = i915_driver_irq_handler,
.reclaim_buffers = drm_core_reclaim_buffers,
.get_map_ofs = drm_core_get_map_ofs,
.get_reg_ofs = drm_core_get_reg_ofs,
.fb_probe = intelfb_probe,
.fb_remove = intelfb_remove,
.fb_resize = intelfb_resize,
.master_create = i915_master_create,
.master_destroy = i915_master_destroy,
#if defined(CONFIG_DEBUG_FS)
.debugfs_init = i915_debugfs_init,
.debugfs_cleanup = i915_debugfs_cleanup,
#endif
.gem_init_object = i915_gem_init_object,
.gem_free_object = i915_gem_free_object,
.gem_vm_ops = &amp;i915_gem_vm_ops,
.ioctls = i915_ioctls,
.fops = {
.owner = THIS_MODULE,
.open = drm_open,
.release = drm_release,
.ioctl = drm_ioctl,
.mmap = drm_mmap,
.poll = drm_poll,
.fasync = drm_fasync,
#ifdef CONFIG_COMPAT
.compat_ioctl = i915_compat_ioctl,
#endif
},
.pci_driver = {
.name = DRIVER_NAME,
.id_table = pciidlist,
.probe = probe,
.remove = __devexit_p(drm_cleanup_pci),
},
.name = DRIVER_NAME,
.desc = DRIVER_DESC,
.date = DRIVER_DATE,
.major = DRIVER_MAJOR,
.minor = DRIVER_MINOR,
.patchlevel = DRIVER_PATCHLEVEL,
};
</programlisting>
<para>
In the example above, taken from the i915 DRM driver, the driver
sets several flags indicating what core features it supports.
We'll go over the individual callbacks in later sections. Since
flags indicate which features your driver supports to the DRM
core, you need to set most of them prior to calling drm_init(). Some,
like DRIVER_MODESET can be set later based on user supplied parameters,
but that's the exception rather than the rule.
</para>
<variablelist>
<title>Driver flags</title>
<varlistentry>
<term>DRIVER_USE_AGP</term>
<listitem><para>
Driver uses AGP interface
</para></listitem>
</varlistentry>
<varlistentry>
<term>DRIVER_REQUIRE_AGP</term>
<listitem><para>
Driver needs AGP interface to function.
</para></listitem>
</varlistentry>
<varlistentry>
<term>DRIVER_USE_MTRR</term>
<listitem>
<para>
Driver uses MTRR interface for mapping memory. Deprecated.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>DRIVER_PCI_DMA</term>
<listitem><para>
Driver is capable of PCI DMA. Deprecated.
</para></listitem>
</varlistentry>
<varlistentry>
<term>DRIVER_SG</term>
<listitem><para>
Driver can perform scatter/gather DMA. Deprecated.
</para></listitem>
</varlistentry>
<varlistentry>
<term>DRIVER_HAVE_DMA</term>
<listitem><para>Driver supports DMA. Deprecated.</para></listitem>
</varlistentry>
<varlistentry>
<term>DRIVER_HAVE_IRQ</term><term>DRIVER_IRQ_SHARED</term>
<listitem>
<para>
DRIVER_HAVE_IRQ indicates whether the driver has a IRQ
handler, DRIVER_IRQ_SHARED indicates whether the device &amp;
handler support shared IRQs (note that this is required of
PCI drivers).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>DRIVER_DMA_QUEUE</term>
<listitem>
<para>
If the driver queues DMA requests and completes them
asynchronously, this flag should be set. Deprecated.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>DRIVER_FB_DMA</term>
<listitem>
<para>
Driver supports DMA to/from the framebuffer. Deprecated.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>DRIVER_MODESET</term>
<listitem>
<para>
Driver supports mode setting interfaces.
</para>
</listitem>
</varlistentry>
</variablelist>
<para>
In this specific case, the driver requires AGP and supports
IRQs. DMA, as we'll see, is handled by device specific ioctls
in this case. It also supports the kernel mode setting APIs, though
unlike in the actual i915 driver source, this example unconditionally
exports KMS capability.
</para>
</sect1>
<!-- Internals: driver load -->
<sect1>
<title>Driver load</title>
<para>
In the previous section, we saw what a typical drm_driver
structure might look like. One of the more important fields in
the structure is the hook for the load function.
</para>
<programlisting>
static struct drm_driver driver = {
...
.load = i915_driver_load,
...
};
</programlisting>
<para>
The load function has many responsibilities: allocating a driver
private structure, specifying supported performance counters,
configuring the device (e.g. mapping registers &amp; command
buffers), initializing the memory manager, and setting up the
initial output configuration.
</para>
<para>
Note that the tasks performed at driver load time must not
conflict with DRM client requirements. For instance, if user
level mode setting drivers are in use, it would be problematic
to perform output discovery &amp; configuration at load time.
Likewise, if pre-memory management aware user level drivers are
in use, memory management and command buffer setup may need to
be omitted. These requirements are driver specific, and care
needs to be taken to keep both old and new applications and
libraries working. The i915 driver supports the "modeset"
module parameter to control whether advanced features are
enabled at load time or in legacy fashion. If compatibility is
a concern (e.g. with drivers converted over to the new interfaces
from the old ones), care must be taken to prevent incompatible
device initialization and control with the currently active
userspace drivers.
</para>
<sect2>
<title>Driver private &amp; performance counters</title>
<para>
The driver private hangs off the main drm_device structure and
can be used for tracking various device specific bits of
information, like register offsets, command buffer status,
register state for suspend/resume, etc. At load time, a
driver can simply allocate one and set drm_device.dev_priv
appropriately; at unload the driver can free it and set
drm_device.dev_priv to NULL.
</para>
<para>
The DRM supports several counters which can be used for rough
performance characterization. Note that the DRM stat counter
system is not often used by applications, and supporting
additional counters is completely optional.
</para>
<para>
These interfaces are deprecated and should not be used. If performance
monitoring is desired, the developer should investigate and
potentially enhance the kernel perf and tracing infrastructure to export
GPU related performance information to performance monitoring
tools and applications.
</para>
</sect2>
<sect2>
<title>Configuring the device</title>
<para>
Obviously, device configuration will be device specific.
However, there are several common operations: finding a
device's PCI resources, mapping them, and potentially setting
up an IRQ handler.
</para>
<para>
Finding &amp; mapping resources is fairly straightforward. The
DRM wrapper functions, drm_get_resource_start() and
drm_get_resource_len() can be used to find BARs on the given
drm_device struct. Once those values have been retrieved, the
driver load function can call drm_addmap() to create a new
mapping for the BAR in question. Note you'll probably want a
drm_local_map_t in your driver private structure to track any
mappings you create.
<!-- !Fdrivers/gpu/drm/drm_bufs.c drm_get_resource_* -->
<!-- !Finclude/drm/drmP.h drm_local_map_t -->
</para>
<para>
if compatibility with other operating systems isn't a concern
(DRM drivers can run under various BSD variants and OpenSolaris),
native Linux calls can be used for the above, e.g. pci_resource_*
and iomap*/iounmap. See the Linux device driver book for more
info.
</para>
<para>
Once you have a register map, you can use the DRM_READn() and
DRM_WRITEn() macros to access the registers on your device, or
use driver specific versions to offset into your MMIO space
relative to a driver specific base pointer (see I915_READ for
example).
</para>
<para>
If your device supports interrupt generation, you may want to
setup an interrupt handler at driver load time as well. This
is done using the drm_irq_install() function. If your device
supports vertical blank interrupts, it should call
drm_vblank_init() to initialize the core vblank handling code before
enabling interrupts on your device. This ensures the vblank related
structures are allocated and allows the core to handle vblank events.
</para>
<!--!Fdrivers/char/drm/drm_irq.c drm_irq_install-->
<para>
Once your interrupt handler is registered (it'll use your
drm_driver.irq_handler as the actual interrupt handling
function), you can safely enable interrupts on your device,
assuming any other state your interrupt handler uses is also
initialized.
</para>
<para>
Another task that may be necessary during configuration is
mapping the video BIOS. On many devices, the VBIOS describes
device configuration, LCD panel timings (if any), and contains
flags indicating device state. Mapping the BIOS can be done
using the pci_map_rom() call, a convenience function that
takes care of mapping the actual ROM, whether it has been
shadowed into memory (typically at address 0xc0000) or exists
on the PCI device in the ROM BAR. Note that once you've
mapped the ROM and extracted any necessary information, be
sure to unmap it; on many devices the ROM address decoder is
shared with other BARs, so leaving it mapped can cause
undesired behavior like hangs or memory corruption.
<!--!Fdrivers/pci/rom.c pci_map_rom-->
</para>
</sect2>
<sect2>
<title>Memory manager initialization</title>
<para>
In order to allocate command buffers, cursor memory, scanout
buffers, etc., as well as support the latest features provided
by packages like Mesa and the X.Org X server, your driver
should support a memory manager.
</para>
<para>
If your driver supports memory management (it should!), you'll
need to set that up at load time as well. How you intialize
it depends on which memory manager you're using, TTM or GEM.
</para>
<sect3>
<title>TTM initialization</title>
<para>
TTM (for Translation Table Manager) manages video memory and
aperture space for graphics devices. TTM supports both UMA devices
and devices with dedicated video RAM (VRAM), i.e. most discrete
graphics devices. If your device has dedicated RAM, supporting
TTM is desireable. TTM also integrates tightly with your
driver specific buffer execution function. See the radeon
driver for examples.
</para>
<para>
The core TTM structure is the ttm_bo_driver struct. It contains
several fields with function pointers for initializing the TTM,
allocating and freeing memory, waiting for command completion
and fence synchronization, and memory migration. See the
radeon_ttm.c file for an example of usage.
</para>
<para>
The ttm_global_reference structure is made up of several fields:
</para>
<programlisting>
struct ttm_global_reference {
enum ttm_global_types global_type;
size_t size;
void *object;
int (*init) (struct ttm_global_reference *);
void (*release) (struct ttm_global_reference *);
};
</programlisting>
<para>
There should be one global reference structure for your memory
manager as a whole, and there will be others for each object
created by the memory manager at runtime. Your global TTM should
have a type of TTM_GLOBAL_TTM_MEM. The size field for the global
object should be sizeof(struct ttm_mem_global), and the init and
release hooks should point at your driver specific init and
release routines, which will probably eventually call
ttm_mem_global_init and ttm_mem_global_release respectively.
</para>
<para>
Once your global TTM accounting structure is set up and initialized
(done by calling ttm_global_item_ref on the global object you
just created), you'll need to create a buffer object TTM to
provide a pool for buffer object allocation by clients and the
kernel itself. The type of this object should be TTM_GLOBAL_TTM_BO,
and its size should be sizeof(struct ttm_bo_global). Again,
driver specific init and release functions can be provided,
likely eventually calling ttm_bo_global_init and
ttm_bo_global_release, respectively. Also like the previous
object, ttm_global_item_ref is used to create an initial reference
count for the TTM, which will call your initalization function.
</para>
</sect3>
<sect3>
<title>GEM initialization</title>
<para>
GEM is an alternative to TTM, designed specifically for UMA
devices. It has simpler initialization and execution requirements
than TTM, but has no VRAM management capability. Core GEM
initialization is comprised of a basic drm_mm_init call to create
a GTT DRM MM object, which provides an address space pool for
object allocation. In a KMS configuration, the driver will
need to allocate and initialize a command ring buffer following
basic GEM initialization. Most UMA devices have a so-called
"stolen" memory region, which provides space for the initial
framebuffer and large, contiguous memory regions required by the
device. This space is not typically managed by GEM, and must
be initialized separately into its own DRM MM object.
</para>
<para>
Initialization will be driver specific, and will depend on
the architecture of the device. In the case of Intel
integrated graphics chips like 965GM, GEM initialization can
be done by calling the internal GEM init function,
i915_gem_do_init(). Since the 965GM is a UMA device
(i.e. it doesn't have dedicated VRAM), GEM will manage
making regular RAM available for GPU operations. Memory set
aside by the BIOS (called "stolen" memory by the i915
driver) will be managed by the DRM memrange allocator; the
rest of the aperture will be managed by GEM.
<programlisting>
/* Basic memrange allocator for stolen space (aka vram) */
drm_memrange_init(&amp;dev_priv->vram, 0, prealloc_size);
/* Let GEM Manage from end of prealloc space to end of aperture */
i915_gem_do_init(dev, prealloc_size, agp_size);
</programlisting>
<!--!Edrivers/char/drm/drm_memrange.c-->
</para>
<para>
Once the memory manager has been set up, we can allocate the
command buffer. In the i915 case, this is also done with a
GEM function, i915_gem_init_ringbuffer().
</para>
</sect3>
</sect2>
<sect2>
<title>Output configuration</title>
<para>
The final initialization task is output configuration. This involves
finding and initializing the CRTCs, encoders and connectors
for your device, creating an initial configuration and
registering a framebuffer console driver.
</para>
<sect3>
<title>Output discovery and initialization</title>
<para>
Several core functions exist to create CRTCs, encoders and
connectors, namely drm_crtc_init(), drm_connector_init() and
drm_encoder_init(), along with several "helper" functions to
perform common tasks.
</para>
<para>
Connectors should be registered with sysfs once they've been
detected and initialized, using the
drm_sysfs_connector_add() function. Likewise, when they're
removed from the system, they should be destroyed with
drm_sysfs_connector_remove().
</para>
<programlisting>
<![CDATA[
void intel_crt_init(struct drm_device *dev)
{
struct drm_connector *connector;
struct intel_output *intel_output;
intel_output = kzalloc(sizeof(struct intel_output), GFP_KERNEL);
if (!intel_output)
return;
connector = &intel_output->base;
drm_connector_init(dev, &intel_output->base,
&intel_crt_connector_funcs, DRM_MODE_CONNECTOR_VGA);
drm_encoder_init(dev, &intel_output->enc, &intel_crt_enc_funcs,
DRM_MODE_ENCODER_DAC);
drm_mode_connector_attach_encoder(&intel_output->base,
&intel_output->enc);
/* Set up the DDC bus. */
intel_output->ddc_bus = intel_i2c_create(dev, GPIOA, "CRTDDC_A");
if (!intel_output->ddc_bus) {
dev_printk(KERN_ERR, &dev->pdev->dev, "DDC bus registration "
"failed.\n");
return;
}
intel_output->type = INTEL_OUTPUT_ANALOG;
connector->interlace_allowed = 0;
connector->doublescan_allowed = 0;
drm_encoder_helper_add(&intel_output->enc, &intel_crt_helper_funcs);
drm_connector_helper_add(connector, &intel_crt_connector_helper_funcs);
drm_sysfs_connector_add(connector);
}
]]>
</programlisting>
<para>
In the example above (again, taken from the i915 driver), a
CRT connector and encoder combination is created. A device
specific i2c bus is also created, for fetching EDID data and
performing monitor detection. Once the process is complete,
the new connector is regsitered with sysfs, to make its
properties available to applications.
</para>
<sect4>
<title>Helper functions and core functions</title>
<para>
Since many PC-class graphics devices have similar display output
designs, the DRM provides a set of helper functions to make
output management easier. The core helper routines handle
encoder re-routing and disabling of unused functions following
mode set. Using the helpers is optional, but recommended for
devices with PC-style architectures (i.e. a set of display planes
for feeding pixels to encoders which are in turn routed to
connectors). Devices with more complex requirements needing
finer grained management can opt to use the core callbacks
directly.
</para>
<para>
[Insert typical diagram here.] [Insert OMAP style config here.]
</para>
</sect4>
<para>
For each encoder, CRTC and connector, several functions must
be provided, depending on the object type. Encoder objects
need should provide a DPMS (basically on/off) function, mode fixup
(for converting requested modes into native hardware timings),
and prepare, set and commit functions for use by the core DRM
helper functions. Connector helpers need to provide mode fetch and
validity functions as well as an encoder matching function for
returing an ideal encoder for a given connector. The core
connector functions include a DPMS callback, (deprecated)
save/restore routines, detection, mode probing, property handling,
and cleanup functions.
</para>
<!--!Edrivers/char/drm/drm_crtc.h-->
<!--!Edrivers/char/drm/drm_crtc.c-->
<!--!Edrivers/char/drm/drm_crtc_helper.c-->
</sect3>
</sect2>
</sect1>
<!-- Internals: vblank handling -->
<sect1>
<title>VBlank event handling</title>
<para>
The DRM core exposes two vertical blank related ioctls:
DRM_IOCTL_WAIT_VBLANK and DRM_IOCTL_MODESET_CTL.
<!--!Edrivers/char/drm/drm_irq.c-->
</para>
<para>
DRM_IOCTL_WAIT_VBLANK takes a struct drm_wait_vblank structure
as its argument, and is used to block or request a signal when a
specified vblank event occurs.
</para>
<para>
DRM_IOCTL_MODESET_CTL should be called by application level
drivers before and after mode setting, since on many devices the
vertical blank counter will be reset at that time. Internally,
the DRM snapshots the last vblank count when the ioctl is called
with the _DRM_PRE_MODESET command so that the counter won't go
backwards (which is dealt with when _DRM_POST_MODESET is used).
</para>
<para>
To support the functions above, the DRM core provides several
helper functions for tracking vertical blank counters, and
requires drivers to provide several callbacks:
get_vblank_counter(), enable_vblank() and disable_vblank(). The
core uses get_vblank_counter() to keep the counter accurate
across interrupt disable periods. It should return the current
vertical blank event count, which is often tracked in a device
register. The enable and disable vblank callbacks should enable
and disable vertical blank interrupts, respectively. In the
absence of DRM clients waiting on vblank events, the core DRM
code will use the disable_vblank() function to disable
interrupts, which saves power. They'll be re-enabled again when
a client calls the vblank wait ioctl above.
</para>
<para>
Devices that don't provide a count register can simply use an
internal atomic counter incremented on every vertical blank
interrupt, and can make their enable and disable vblank
functions into no-ops.
</para>
</sect1>
<sect1>
<title>Memory management</title>
<para>
The memory manager lies at the heart of many DRM operations, and
is also required to support advanced client features like OpenGL
pbuffers. The DRM currently contains two memory managers, TTM
and GEM.
</para>
<sect2>
<title>The Translation Table Manager (TTM)</title>
<para>
TTM was developed by Tungsten Graphics, primarily by Thomas
Hellström, and is intended to be a flexible, high performance
graphics memory manager.
</para>
<para>
Drivers wishing to support TTM must fill out a drm_bo_driver
structure.
</para>
<para>
TTM design background and information belongs here.
</para>
</sect2>
<sect2>
<title>The Graphics Execution Manager (GEM)</title>
<para>
GEM is an Intel project, authored by Eric Anholt and Keith
Packard. It provides simpler interfaces than TTM, and is well
suited for UMA devices.
</para>
<para>
GEM-enabled drivers must provide gem_init_object() and
gem_free_object() callbacks to support the core memory
allocation routines. They should also provide several driver
specific ioctls to support command execution, pinning, buffer
read &amp; write, mapping, and domain ownership transfers.
</para>
<para>
On a fundamental level, GEM involves several operations: memory
allocation and freeing, command execution, and aperture management
at command execution time. Buffer object allocation is relatively
straightforward and largely provided by Linux's shmem layer, which
provides memory to back each object. When mapped into the GTT
or used in a command buffer, the backing pages for an object are
flushed to memory and marked write combined so as to be coherent
with the GPU. Likewise, when the GPU finishes rendering to an object,
if the CPU accesses it, it must be made coherent with the CPU's view
of memory, usually involving GPU cache flushing of various kinds.
This core CPU&lt;-&gt;GPU coherency management is provided by the GEM
set domain function, which evaluates an object's current domain and
performs any necessary flushing or synchronization to put the object
into the desired coherency domain (note that the object may be busy,
i.e. an active render target; in that case the set domain function
will block the client and wait for rendering to complete before
performing any necessary flushing operations).
</para>
<para>
Perhaps the most important GEM function is providing a command
execution interface to clients. Client programs construct command
buffers containing references to previously allocated memory objects
and submit them to GEM. At that point, GEM will take care to bind
all the objects into the GTT, execute the buffer, and provide
necessary synchronization between clients accessing the same buffers.
This often involves evicting some objects from the GTT and re-binding
others (a fairly expensive operation), and providing relocation
support which hides fixed GTT offsets from clients. Clients must
take care not to submit command buffers that reference more objects
than can fit in the GTT or GEM will reject them and no rendering
will occur. Similarly, if several objects in the buffer require
fence registers to be allocated for correct rendering (e.g. 2D blits
on pre-965 chips), care must be taken not to require more fence
registers than are available to the client. Such resource management
should be abstracted from the client in libdrm.
</para>
</sect2>
</sect1>
<!-- Output management -->
<sect1>
<title>Output management</title>
<para>
At the core of the DRM output management code is a set of
structures representing CRTCs, encoders and connectors.
</para>
<para>
A CRTC is an abstraction representing a part of the chip that
contains a pointer to a scanout buffer. Therefore, the number
of CRTCs available determines how many independent scanout
buffers can be active at any given time. The CRTC structure
contains several fields to support this: a pointer to some video
memory, a display mode, and an (x, y) offset into the video
memory to support panning or configurations where one piece of
video memory spans multiple CRTCs.
</para>
<para>
An encoder takes pixel data from a CRTC and converts it to a
format suitable for any attached connectors. On some devices,
it may be possible to have a CRTC send data to more than one
encoder. In that case, both encoders would receive data from
the same scanout buffer, resulting in a "cloned" display
configuration across the connectors attached to each encoder.
</para>
<para>
A connector is the final destination for pixel data on a device,
and usually connects directly to an external display device like
a monitor or laptop panel. A connector can only be attached to
one encoder at a time. The connector is also the structure
where information about the attached display is kept, so it
contains fields for display data, EDID data, DPMS &amp;
connection status, and information about modes supported on the
attached displays.
</para>
<!--!Edrivers/char/drm/drm_crtc.c-->
</sect1>
<sect1>
<title>Framebuffer management</title>
<para>
In order to set a mode on a given CRTC, encoder and connector
configuration, clients need to provide a framebuffer object which
will provide a source of pixels for the CRTC to deliver to the encoder(s)
and ultimately the connector(s) in the configuration. A framebuffer
is fundamentally a driver specific memory object, made into an opaque
handle by the DRM addfb function. Once an fb has been created this
way it can be passed to the KMS mode setting routines for use in
a configuration.
</para>
</sect1>
<sect1>
<title>Command submission &amp; fencing</title>
<para>
This should cover a few device specific command submission
implementations.
</para>
</sect1>
<sect1>
<title>Suspend/resume</title>
<para>
The DRM core provides some suspend/resume code, but drivers
wanting full suspend/resume support should provide save() and
restore() functions. These will be called at suspend,
hibernate, or resume time, and should perform any state save or
restore required by your device across suspend or hibernate
states.
</para>
</sect1>
<sect1>
<title>DMA services</title>
<para>
This should cover how DMA mapping etc. is supported by the core.
These functions are deprecated and should not be used.
</para>
</sect1>
</chapter>
<!-- External interfaces -->
<chapter id="drmExternals">
<title>Userland interfaces</title>
<para>
The DRM core exports several interfaces to applications,
generally intended to be used through corresponding libdrm
wrapper functions. In addition, drivers export device specific
interfaces for use by userspace drivers &amp; device aware
applications through ioctls and sysfs files.
</para>
<para>
External interfaces include: memory mapping, context management,
DMA operations, AGP management, vblank control, fence
management, memory management, and output management.
</para>
<para>
Cover generic ioctls and sysfs layout here. Only need high
level info, since man pages will cover the rest.
</para>
</chapter>
<!-- API reference -->
<appendix id="drmDriverApi">
<title>DRM Driver API</title>
<para>
Include auto-generated API reference here (need to reference it
from paragraphs above too).
</para>
</appendix>
</book>

712
Documentation/DocBook/kgdb.tmpl
View File

@ -4,7 +4,7 @@
<book id="kgdbOnLinux">
<bookinfo>
<title>Using kgdb and the kgdb Internals</title>
<title>Using kgdb, kdb and the kernel debugger internals</title>
<authorgroup>
<author>
@ -17,33 +17,8 @@
</affiliation>
</author>
</authorgroup>
<authorgroup>
<author>
<firstname>Tom</firstname>
<surname>Rini</surname>
<affiliation>
<address>
<email>trini@kernel.crashing.org</email>
</address>
</affiliation>
</author>
</authorgroup>
<authorgroup>
<author>
<firstname>Amit S.</firstname>
<surname>Kale</surname>
<affiliation>
<address>
<email>amitkale@linsyssoft.com</email>
</address>
</affiliation>
</author>
</authorgroup>
<copyright>
<year>2008</year>
<year>2008,2010</year>
<holder>Wind River Systems, Inc.</holder>
</copyright>
<copyright>
@ -69,41 +44,76 @@
<chapter id="Introduction">
<title>Introduction</title>
<para>
kgdb is a source level debugger for linux kernel. It is used along
with gdb to debug a linux kernel. The expectation is that gdb can
be used to "break in" to the kernel to inspect memory, variables
and look through call stack information similar to what an
application developer would use gdb for. It is possible to place
breakpoints in kernel code and perform some limited execution
stepping.
The kernel has two different debugger front ends (kdb and kgdb)
which interface to the debug core. It is possible to use either
of the debugger front ends and dynamically transition between them
if you configure the kernel properly at compile and runtime.
</para>
<para>
Two machines are required for using kgdb. One of these machines is a
development machine and the other is a test machine. The kernel
to be debugged runs on the test machine. The development machine
runs an instance of gdb against the vmlinux file which contains
the symbols (not boot image such as bzImage, zImage, uImage...).
In gdb the developer specifies the connection parameters and
connects to kgdb. The type of connection a developer makes with
gdb depends on the availability of kgdb I/O modules compiled as
builtin's or kernel modules in the test machine's kernel.
Kdb is simplistic shell-style interface which you can use on a
system console with a keyboard or serial console. You can use it
to inspect memory, registers, process lists, dmesg, and even set
breakpoints to stop in a certain location. Kdb is not a source
level debugger, although you can set breakpoints and execute some
basic kernel run control. Kdb is mainly aimed at doing some
analysis to aid in development or diagnosing kernel problems. You
can access some symbols by name in kernel built-ins or in kernel
modules if the code was built
with <symbol>CONFIG_KALLSYMS</symbol>.
</para>
<para>
Kgdb is intended to be used as a source level debugger for the
Linux kernel. It is used along with gdb to debug a Linux kernel.
The expectation is that gdb can be used to "break in" to the
kernel to inspect memory, variables and look through call stack
information similar to the way an application developer would use
gdb to debug an application. It is possible to place breakpoints
in kernel code and perform some limited execution stepping.
</para>
<para>
Two machines are required for using kgdb. One of these machines is
a development machine and the other is the target machine. The
kernel to be debugged runs on the target machine. The development
machine runs an instance of gdb against the vmlinux file which
contains the symbols (not boot image such as bzImage, zImage,
uImage...). In gdb the developer specifies the connection
parameters and connects to kgdb. The type of connection a
developer makes with gdb depends on the availability of kgdb I/O
modules compiled as built-ins or loadable kernel modules in the test
machine's kernel.
</para>
</chapter>
<chapter id="CompilingAKernel">
<title>Compiling a kernel</title>
<title>Compiling a kernel</title>
<para>
<itemizedlist>
<listitem><para>In order to enable compilation of kdb, you must first enable kgdb.</para></listitem>
<listitem><para>The kgdb test compile options are described in the kgdb test suite chapter.</para></listitem>
</itemizedlist>
</para>
<sect1 id="CompileKGDB">
<title>Kernel config options for kgdb</title>
<para>
To enable <symbol>CONFIG_KGDB</symbol> you should first turn on
"Prompt for development and/or incomplete code/drivers"
(CONFIG_EXPERIMENTAL) in "General setup", then under the
"Kernel debugging" select "KGDB: kernel debugging with remote gdb".
"Kernel debugging" select "KGDB: kernel debugger".
</para>
<para>
While it is not a hard requirement that you have symbols in your
vmlinux file, gdb tends not to be very useful without the symbolic
data, so you will want to turn
on <symbol>CONFIG_DEBUG_INFO</symbol> which is called "Compile the
kernel with debug info" in the config menu.
</para>
<para>
It is advised, but not required that you turn on the
CONFIG_FRAME_POINTER kernel option. This option inserts code to
into the compiled executable which saves the frame information in
registers or on the stack at different points which will allow a
debugger such as gdb to more accurately construct stack back traces
while debugging the kernel.
<symbol>CONFIG_FRAME_POINTER</symbol> kernel option which is called "Compile the
kernel with frame pointers" in the config menu. This option
inserts code to into the compiled executable which saves the frame
information in registers or on the stack at different points which
allows a debugger such as gdb to more accurately construct
stack back traces while debugging the kernel.
</para>
<para>
If the architecture that you are using supports the kernel option
@ -116,38 +126,160 @@
this option.
</para>
<para>
Next you should choose one of more I/O drivers to interconnect debugging
host and debugged target. Early boot debugging requires a KGDB
I/O driver that supports early debugging and the driver must be
built into the kernel directly. Kgdb I/O driver configuration
takes place via kernel or module parameters, see following
chapter.
Next you should choose one of more I/O drivers to interconnect
debugging host and debugged target. Early boot debugging requires
a KGDB I/O driver that supports early debugging and the driver
must be built into the kernel directly. Kgdb I/O driver
configuration takes place via kernel or module parameters which
you can learn more about in the in the section that describes the
parameter "kgdboc".
</para>
<para>
The kgdb test compile options are described in the kgdb test suite chapter.
<para>Here is an example set of .config symbols to enable or
disable for kgdb:
<itemizedlist>
<listitem><para># CONFIG_DEBUG_RODATA is not set</para></listitem>
<listitem><para>CONFIG_FRAME_POINTER=y</para></listitem>
<listitem><para>CONFIG_KGDB=y</para></listitem>
<listitem><para>CONFIG_KGDB_SERIAL_CONSOLE=y</para></listitem>
</itemizedlist>
</para>
</sect1>
<sect1 id="CompileKDB">
<title>Kernel config options for kdb</title>
<para>Kdb is quite a bit more complex than the simple gdbstub
sitting on top of the kernel's debug core. Kdb must implement a
shell, and also adds some helper functions in other parts of the
kernel, responsible for printing out interesting data such as what
you would see if you ran "lsmod", or "ps". In order to build kdb
into the kernel you follow the same steps as you would for kgdb.
</para>
<para>The main config option for kdb
is <symbol>CONFIG_KGDB_KDB</symbol> which is called "KGDB_KDB:
include kdb frontend for kgdb" in the config menu. In theory you
would have already also selected an I/O driver such as the
CONFIG_KGDB_SERIAL_CONSOLE interface if you plan on using kdb on a
serial port, when you were configuring kgdb.
</para>
<para>If you want to use a PS/2-style keyboard with kdb, you would
select CONFIG_KDB_KEYBOARD which is called "KGDB_KDB: keyboard as
input device" in the config menu. The CONFIG_KDB_KEYBOARD option
is not used for anything in the gdb interface to kgdb. The
CONFIG_KDB_KEYBOARD option only works with kdb.
</para>
<para>Here is an example set of .config symbols to enable/disable kdb:
<itemizedlist>
<listitem><para># CONFIG_DEBUG_RODATA is not set</para></listitem>
<listitem><para>CONFIG_FRAME_POINTER=y</para></listitem>
<listitem><para>CONFIG_KGDB=y</para></listitem>
<listitem><para>CONFIG_KGDB_SERIAL_CONSOLE=y</para></listitem>
<listitem><para>CONFIG_KGDB_KDB=y</para></listitem>
<listitem><para>CONFIG_KDB_KEYBOARD=y</para></listitem>
</itemizedlist>
</para>
</sect1>
</chapter>
<chapter id="EnableKGDB">
<title>Enable kgdb for debugging</title>
<para>
In order to use kgdb you must activate it by passing configuration
information to one of the kgdb I/O drivers. If you do not pass any
configuration information kgdb will not do anything at all. Kgdb
will only actively hook up to the kernel trap hooks if a kgdb I/O
driver is loaded and configured. If you unconfigure a kgdb I/O
driver, kgdb will unregister all the kernel hook points.
<chapter id="kgdbKernelArgs">
<title>Kernel Debugger Boot Arguments</title>
<para>This section describes the various runtime kernel
parameters that affect the configuration of the kernel debugger.
The following chapter covers using kdb and kgdb as well as
provides some examples of the configuration parameters.</para>
<sect1 id="kgdboc">
<title>Kernel parameter: kgdboc</title>
<para>The kgdboc driver was originally an abbreviation meant to
stand for "kgdb over console". Today it is the primary mechanism
to configure how to communicate from gdb to kgdb as well as the
devices you want to use to interact with the kdb shell.
</para>
<para>
All drivers can be reconfigured at run time, if
<symbol>CONFIG_SYSFS</symbol> and <symbol>CONFIG_MODULES</symbol>
are enabled, by echo'ing a new config string to
<constant>/sys/module/&lt;driver&gt;/parameter/&lt;option&gt;</constant>.
The driver can be unconfigured by passing an empty string. You cannot
change the configuration while the debugger is attached. Make sure
to detach the debugger with the <constant>detach</constant> command
prior to trying unconfigure a kgdb I/O driver.
<para>For kgdb/gdb, kgdboc is designed to work with a single serial
port. It is intended to cover the circumstance where you want to
use a serial console as your primary console as well as using it to
perform kernel debugging. It is also possible to use kgdb on a
serial port which is not designated as a system console. Kgdboc
may be configured as a kernel built-in or a kernel loadable module.
You can only make use of <constant>kgdbwait</constant> and early
debugging if you build kgdboc into the kernel as a built-in.
</para>
<sect2 id="kgdbocArgs">
<title>kgdboc arguments</title>
<para>Usage: <constant>kgdboc=[kbd][[,]serial_device][,baud]</constant></para>
<sect3 id="kgdbocArgs1">
<title>Using loadable module or built-in</title>
<para>
<orderedlist>
<listitem><para>As a kernel built-in:</para>
<para>Use the kernel boot argument: <constant>kgdboc=&lt;tty-device&gt;,[baud]</constant></para></listitem>
<listitem>
<para>As a kernel loadable module:</para>
<para>Use the command: <constant>modprobe kgdboc kgdboc=&lt;tty-device&gt;,[baud]</constant></para>
<para>Here are two examples of how you might formate the kgdboc
string. The first is for an x86 target using the first serial port.
The second example is for the ARM Versatile AB using the second
serial port.
<orderedlist>
<listitem><para><constant>kgdboc=ttyS0,115200</constant></para></listitem>
<listitem><para><constant>kgdboc=ttyAMA1,115200</constant></para></listitem>
</orderedlist>
</para>
</listitem>
</orderedlist></para>
</sect3>
<sect3 id="kgdbocArgs2">
<title>Configure kgdboc at runtime with sysfs</title>
<para>At run time you can enable or disable kgdboc by echoing a
parameters into the sysfs. Here are two examples:</para>
<orderedlist>
<listitem><para>Enable kgdboc on ttyS0</para>
<para><constant>echo ttyS0 &gt; /sys/module/kgdboc/parameters/kgdboc</constant></para></listitem>
<listitem><para>Disable kgdboc</para>
<para><constant>echo "" &gt; /sys/module/kgdboc/parameters/kgdboc</constant></para></listitem>
</orderedlist>
<para>NOTE: You do not need to specify the baud if you are
configuring the console on tty which is already configured or
open.</para>
</sect3>
<sect3 id="kgdbocArgs3">
<title>More examples</title>
<para>You can configure kgdboc to use the keyboard, and or a serial device
depending on if you are using kdb and or kgdb, in one of the
following scenarios.
<orderedlist>
<listitem><para>kdb and kgdb over only a serial port</para>
<para><constant>kgdboc=&lt;serial_device&gt;[,baud]</constant></para>
<para>Example: <constant>kgdboc=ttyS0,115200</constant></para>
</listitem>
<listitem><para>kdb and kgdb with keyboard and a serial port</para>
<para><constant>kgdboc=kbd,&lt;serial_device&gt;[,baud]</constant></para>
<para>Example: <constant>kgdboc=kbd,ttyS0,115200</constant></para>
</listitem>
<listitem><para>kdb with a keyboard</para>
<para><constant>kgdboc=kbd</constant></para>
</listitem>
</orderedlist>
</para>
</sect3>
<para>NOTE: Kgdboc does not support interrupting the target via the
gdb remote protocol. You must manually send a sysrq-g unless you
have a proxy that splits console output to a terminal program.
A console proxy has a separate TCP port for the debugger and a separate
TCP port for the "human" console. The proxy can take care of sending
the sysrq-g for you.
</para>
<para>When using kgdboc with no debugger proxy, you can end up
connecting the debugger at one of two entry points. If an
exception occurs after you have loaded kgdboc, a message should
print on the console stating it is waiting for the debugger. In
this case you disconnect your terminal program and then connect the
debugger in its place. If you want to interrupt the target system
and forcibly enter a debug session you have to issue a Sysrq
sequence and then type the letter <constant>g</constant>. Then
you disconnect the terminal session and connect gdb. Your options
if you don't like this are to hack gdb to send the sysrq-g for you
as well as on the initial connect, or to use a debugger proxy that
allows an unmodified gdb to do the debugging.
</para>
</sect2>
</sect1>
<sect1 id="kgdbwait">
<title>Kernel parameter: kgdbwait</title>
<para>
@ -162,103 +294,204 @@
</para>
<para>
The kernel will stop and wait as early as the I/O driver and
architecture will allow when you use this option. If you build the
kgdb I/O driver as a kernel module kgdbwait will not do anything.
architecture allows when you use this option. If you build the
kgdb I/O driver as a loadable kernel module kgdbwait will not do
anything.
</para>
</sect1>
<sect1 id="kgdboc">
<title>Kernel parameter: kgdboc</title>
<para>
The kgdboc driver was originally an abbreviation meant to stand for
"kgdb over console". Kgdboc is designed to work with a single
serial port. It was meant to cover the circumstance
where you wanted to use a serial console as your primary console as
well as using it to perform kernel debugging. Of course you can
also use kgdboc without assigning a console to the same port.
</para>
<sect2 id="UsingKgdboc">
<title>Using kgdboc</title>
<para>
You can configure kgdboc via sysfs or a module or kernel boot line
parameter depending on if you build with CONFIG_KGDBOC as a module
or built-in.
<orderedlist>
<listitem><para>From the module load or build-in</para>
<para><constant>kgdboc=&lt;tty-device&gt;,[baud]</constant></para>
<para>
The example here would be if your console port was typically ttyS0, you would use something like <constant>kgdboc=ttyS0,115200</constant> or on the ARM Versatile AB you would likely use <constant>kgdboc=ttyAMA0,115200</constant>
</para>
</listitem>
<listitem><para>From sysfs</para>
<para><constant>echo ttyS0 &gt; /sys/module/kgdboc/parameters/kgdboc</constant></para>
</listitem>
</orderedlist>
</para>
<para>
NOTE: Kgdboc does not support interrupting the target via the
gdb remote protocol. You must manually send a sysrq-g unless you
have a proxy that splits console output to a terminal problem and
has a separate port for the debugger to connect to that sends the
sysrq-g for you.
</para>
<para>When using kgdboc with no debugger proxy, you can end up
connecting the debugger for one of two entry points. If an
exception occurs after you have loaded kgdboc a message should print
on the console stating it is waiting for the debugger. In case you
disconnect your terminal program and then connect the debugger in
its place. If you want to interrupt the target system and forcibly
enter a debug session you have to issue a Sysrq sequence and then
type the letter <constant>g</constant>. Then you disconnect the
terminal session and connect gdb. Your options if you don't like
this are to hack gdb to send the sysrq-g for you as well as on the
initial connect, or to use a debugger proxy that allows an
unmodified gdb to do the debugging.
</para>
</sect2>
</sect1>
<sect1 id="kgdbcon">
<title>Kernel parameter: kgdbcon</title>
<para>
Kgdb supports using the gdb serial protocol to send console messages
to the debugger when the debugger is connected and running. There
are two ways to activate this feature.
<orderedlist>
<listitem><para>Activate with the kernel command line option:</para>
<para><constant>kgdbcon</constant></para>
</listitem>
<listitem><para>Use sysfs before configuring an io driver</para>
<para>
<constant>echo 1 &gt; /sys/module/kgdb/parameters/kgdb_use_con</constant>
</para>
<para>
NOTE: If you do this after you configure the kgdb I/O driver, the
setting will not take effect until the next point the I/O is
reconfigured.
</para>
</listitem>
</orderedlist>
</para>
<para>
IMPORTANT NOTE: Using this option with kgdb over the console
(kgdboc) is not supported.
<sect1 id="kgdbcon">
<title>Kernel parameter: kgdbcon</title>
<para> The kgdbcon feature allows you to see printk() messages
inside gdb while gdb is connected to the kernel. Kdb does not make
use of the kgdbcon feature.
</para>
<para>Kgdb supports using the gdb serial protocol to send console
messages to the debugger when the debugger is connected and running.
There are two ways to activate this feature.
<orderedlist>
<listitem><para>Activate with the kernel command line option:</para>
<para><constant>kgdbcon</constant></para>
</listitem>
<listitem><para>Use sysfs before configuring an I/O driver</para>
<para>
<constant>echo 1 &gt; /sys/module/kgdb/parameters/kgdb_use_con</constant>
</para>
<para>
NOTE: If you do this after you configure the kgdb I/O driver, the
setting will not take effect until the next point the I/O is
reconfigured.
</para>
</listitem>
</orderedlist>
<para>IMPORTANT NOTE: You cannot use kgdboc + kgdbcon on a tty that is an
active system console. An example incorrect usage is <constant>console=ttyS0,115200 kgdboc=ttyS0 kgdbcon</constant>
</para>
<para>It is possible to use this option with kgdboc on a tty that is not a system console.
</para>
</para>
</sect1>
</chapter>
<chapter id="ConnectingGDB">
<title>Connecting gdb</title>
<chapter id="usingKDB">
<title>Using kdb</title>
<para>
</para>
<sect1 id="quickKDBserial">
<title>Quick start for kdb on a serial port</title>
<para>This is a quick example of how to use kdb.</para>
<para><orderedlist>
<listitem><para>Boot kernel with arguments:
<itemizedlist>
<listitem><para><constant>console=ttyS0,115200 kgdboc=ttyS0,115200</constant></para></listitem>
</itemizedlist></para>
<para>OR</para>
<para>Configure kgdboc after the kernel booted; assuming you are using a serial port console:
<itemizedlist>
<listitem><para><constant>echo ttyS0 &gt; /sys/module/kgdboc/parameters/kgdboc</constant></para></listitem>
</itemizedlist>
</para>
</listitem>
<listitem><para>Enter the kernel debugger manually or by waiting for an oops or fault. There are several ways you can enter the kernel debugger manually; all involve using the sysrq-g, which means you must have enabled CONFIG_MAGIC_SYSRQ=y in your kernel config.</para>
<itemizedlist>
<listitem><para>When logged in as root or with a super user session you can run:</para>
<para><constant>echo g &gt; /proc/sysrq-trigger</constant></para></listitem>
<listitem><para>Example using minicom 2.2</para>
<para>Press: <constant>Control-a</constant></para>
<para>Press: <constant>f</constant></para>
<para>Press: <constant>g</constant></para>
</listitem>
<listitem><para>When you have telneted to a terminal server that supports sending a remote break</para>
<para>Press: <constant>Control-]</constant></para>
<para>Type in:<constant>send break</constant></para>
<para>Press: <constant>Enter</constant></para>
<para>Press: <constant>g</constant></para>
</listitem>
</itemizedlist>
</listitem>
<listitem><para>From the kdb prompt you can run the "help" command to see a complete list of the commands that are available.</para>
<para>Some useful commands in kdb include:
<itemizedlist>
<listitem><para>lsmod -- Shows where kernel modules are loaded</para></listitem>
<listitem><para>ps -- Displays only the active processes</para></listitem>
<listitem><para>ps A -- Shows all the processes</para></listitem>
<listitem><para>summary -- Shows kernel version info and memory usage</para></listitem>
<listitem><para>bt -- Get a backtrace of the current process using dump_stack()</para></listitem>
<listitem><para>dmesg -- View the kernel syslog buffer</para></listitem>
<listitem><para>go -- Continue the system</para></listitem>
</itemizedlist>
</para>
</listitem>
<listitem>
<para>When you are done using kdb you need to consider rebooting the
system or using the "go" command to resuming normal kernel
execution. If you have paused the kernel for a lengthy period of
time, applications that rely on timely networking or anything to do
with real wall clock time could be adversely affected, so you
should take this into consideration when using the kernel
debugger.</para>
</listitem>
</orderedlist></para>
</sect1>
<sect1 id="quickKDBkeyboard">
<title>Quick start for kdb using a keyboard connected console</title>
<para>This is a quick example of how to use kdb with a keyboard.</para>
<para><orderedlist>
<listitem><para>Boot kernel with arguments:
<itemizedlist>
<listitem><para><constant>kgdboc=kbd</constant></para></listitem>
</itemizedlist></para>
<para>OR</para>
<para>Configure kgdboc after the kernel booted:
<itemizedlist>
<listitem><para><constant>echo kbd &gt; /sys/module/kgdboc/parameters/kgdboc</constant></para></listitem>
</itemizedlist>
</para>
</listitem>
<listitem><para>Enter the kernel debugger manually or by waiting for an oops or fault. There are several ways you can enter the kernel debugger manually; all involve using the sysrq-g, which means you must have enabled CONFIG_MAGIC_SYSRQ=y in your kernel config.</para>
<itemizedlist>
<listitem><para>When logged in as root or with a super user session you can run:</para>
<para><constant>echo g &gt; /proc/sysrq-trigger</constant></para></listitem>
<listitem><para>Example using a laptop keyboard</para>
<para>Press and hold down: <constant>Alt</constant></para>
<para>Press and hold down: <constant>Fn</constant></para>
<para>Press and release the key with the label: <constant>SysRq</constant></para>
<para>Release: <constant>Fn</constant></para>
<para>Press and release: <constant>g</constant></para>
<para>Release: <constant>Alt</constant></para>
</listitem>
<listitem><para>Example using a PS/2 101-key keyboard</para>
<para>Press and hold down: <constant>Alt</constant></para>
<para>Press and release the key with the label: <constant>SysRq</constant></para>
<para>Press and release: <constant>g</constant></para>
<para>Release: <constant>Alt</constant></para>
</listitem>
</itemizedlist>
</listitem>
<listitem>
<para>Now type in a kdb command such as "help", "dmesg", "bt" or "go" to continue kernel execution.</para>
</listitem>
</orderedlist></para>
</sect1>
</chapter>
<chapter id="EnableKGDB">
<title>Using kgdb / gdb</title>
<para>In order to use kgdb you must activate it by passing
configuration information to one of the kgdb I/O drivers. If you
do not pass any configuration information kgdb will not do anything
at all. Kgdb will only actively hook up to the kernel trap hooks
if a kgdb I/O driver is loaded and configured. If you unconfigure
a kgdb I/O driver, kgdb will unregister all the kernel hook points.
</para>
<para> All kgdb I/O drivers can be reconfigured at run time, if
<symbol>CONFIG_SYSFS</symbol> and <symbol>CONFIG_MODULES</symbol>
are enabled, by echo'ing a new config string to
<constant>/sys/module/&lt;driver&gt;/parameter/&lt;option&gt;</constant>.
The driver can be unconfigured by passing an empty string. You cannot
change the configuration while the debugger is attached. Make sure
to detach the debugger with the <constant>detach</constant> command
prior to trying to unconfigure a kgdb I/O driver.
</para>
<sect1 id="ConnectingGDB">
<title>Connecting with gdb to a serial port</title>
<orderedlist>
<listitem><para>Configure kgdboc</para>
<para>Boot kernel with arguments:
<itemizedlist>
<listitem><para><constant>kgdboc=ttyS0,115200</constant></para></listitem>
</itemizedlist></para>
<para>OR</para>
<para>Configure kgdboc after the kernel booted:
<itemizedlist>
<listitem><para><constant>echo ttyS0 &gt; /sys/module/kgdboc/parameters/kgdboc</constant></para></listitem>
</itemizedlist></para>
</listitem>
<listitem>
<para>Stop kernel execution (break into the debugger)</para>
<para>In order to connect to gdb via kgdboc, the kernel must
first be stopped. There are several ways to stop the kernel which
include using kgdbwait as a boot argument, via a sysrq-g, or running
the kernel until it takes an exception where it waits for the
debugger to attach.
<itemizedlist>
<listitem><para>When logged in as root or with a super user session you can run:</para>
<para><constant>echo g &gt; /proc/sysrq-trigger</constant></para></listitem>
<listitem><para>Example using minicom 2.2</para>
<para>Press: <constant>Control-a</constant></para>
<para>Press: <constant>f</constant></para>
<para>Press: <constant>g</constant></para>
</listitem>
<listitem><para>When you have telneted to a terminal server that supports sending a remote break</para>
<para>Press: <constant>Control-]</constant></para>
<para>Type in:<constant>send break</constant></para>
<para>Press: <constant>Enter</constant></para>
<para>Press: <constant>g</constant></para>
</listitem>
</itemizedlist>
</para>
</listitem>
<listitem>
<para>Connect from from gdb</para>
<para>
If you are using kgdboc, you need to have used kgdbwait as a boot
argument, issued a sysrq-g, or the system you are going to debug
has already taken an exception and is waiting for the debugger to
attach before you can connect gdb.
</para>
<para>
If you are not using different kgdb I/O driver other than kgdboc,
you should be able to connect and the target will automatically
respond.
</para>
<para>
Example (using a serial port):
Example (using a directly connected port):
</para>
<programlisting>
% gdb ./vmlinux
@ -266,7 +499,7 @@
(gdb) target remote /dev/ttyS0
</programlisting>
<para>
Example (kgdb to a terminal server on tcp port 2012):
Example (kgdb to a terminal server on TCP port 2012):
</para>
<programlisting>
% gdb ./vmlinux
@ -283,6 +516,83 @@
communications. You do this prior to issuing the <constant>target
remote</constant> command by typing in: <constant>set debug remote 1</constant>
</para>
</listitem>
</orderedlist>
<para>Remember if you continue in gdb, and need to "break in" again,
you need to issue an other sysrq-g. It is easy to create a simple
entry point by putting a breakpoint at <constant>sys_sync</constant>
and then you can run "sync" from a shell or script to break into the
debugger.</para>
</sect1>
</chapter>
<chapter id="switchKdbKgdb">
<title>kgdb and kdb interoperability</title>
<para>It is possible to transition between kdb and kgdb dynamically.
The debug core will remember which you used the last time and
automatically start in the same mode.</para>
<sect1>
<title>Switching between kdb and kgdb</title>
<sect2>
<title>Switching from kgdb to kdb</title>
<para>
There are two ways to switch from kgdb to kdb: you can use gdb to
issue a maintenance packet, or you can blindly type the command $3#33.
Whenever kernel debugger stops in kgdb mode it will print the
message <constant>KGDB or $3#33 for KDB</constant>. It is important
to note that you have to type the sequence correctly in one pass.
You cannot type a backspace or delete because kgdb will interpret
that as part of the debug stream.
<orderedlist>
<listitem><para>Change from kgdb to kdb by blindly typing:</para>
<para><constant>$3#33</constant></para></listitem>
<listitem><para>Change from kgdb to kdb with gdb</para>
<para><constant>maintenance packet 3</constant></para>
<para>NOTE: Now you must kill gdb. Typically you press control-z and
issue the command: kill -9 %</para></listitem>
</orderedlist>
</para>
</sect2>
<sect2>
<title>Change from kdb to kgdb</title>
<para>There are two ways you can change from kdb to kgdb. You can
manually enter kgdb mode by issuing the kgdb command from the kdb
shell prompt, or you can connect gdb while the kdb shell prompt is
active. The kdb shell looks for the typical first commands that gdb
would issue with the gdb remote protocol and if it sees one of those
commands it automatically changes into kgdb mode.</para>
<orderedlist>
<listitem><para>From kdb issue the command:</para>
<para><constant>kgdb</constant></para>
<para>Now disconnect your terminal program and connect gdb in its place</para></listitem>
<listitem><para>At the kdb prompt, disconnect the terminal program and connect gdb in its place.</para></listitem>
</orderedlist>
</sect2>
</sect1>
<sect1>
<title>Running kdb commands from gdb</title>
<para>It is possible to run a limited set of kdb commands from gdb,
using the gdb monitor command. You don't want to execute any of the
run control or breakpoint operations, because it can disrupt the
state of the kernel debugger. You should be using gdb for
breakpoints and run control operations if you have gdb connected.
The more useful commands to run are things like lsmod, dmesg, ps or
possibly some of the memory information commands. To see all the kdb
commands you can run <constant>monitor help</constant>.</para>
<para>Example:
<informalexample><programlisting>
(gdb) monitor ps
1 idle process (state I) and
27 sleeping system daemon (state M) processes suppressed,
use 'ps A' to see all.
Task Addr Pid Parent [*] cpu State Thread Command
0xc78291d0 1 0 0 0 S 0xc7829404 init
0xc7954150 942 1 0 0 S 0xc7954384 dropbear
0xc78789c0 944 1 0 0 S 0xc7878bf4 sh
(gdb)
</programlisting></informalexample>
</para>
</sect1>
</chapter>
<chapter id="KGDBTestSuite">
<title>kgdb Test Suite</title>
@ -309,34 +619,36 @@
</para>
</chapter>
<chapter id="CommonBackEndReq">
<title>KGDB Internals</title>
<title>Kernel Debugger Internals</title>
<sect1 id="kgdbArchitecture">
<title>Architecture Specifics</title>
<para>
Kgdb is organized into three basic components:
The kernel debugger is organized into a number of components:
<orderedlist>
<listitem><para>kgdb core</para>
<listitem><para>The debug core</para>
<para>
The kgdb core is found in kernel/kgdb.c. It contains:
The debug core is found in kernel/debugger/debug_core.c. It contains:
<itemizedlist>
<listitem><para>All the logic to implement the gdb serial protocol</para></listitem>
<listitem><para>A generic OS exception handler which includes sync'ing the processors into a stopped state on an multi cpu system.</para></listitem>
<listitem><para>A generic OS exception handler which includes
sync'ing the processors into a stopped state on an multi-CPU
system.</para></listitem>
<listitem><para>The API to talk to the kgdb I/O drivers</para></listitem>
<listitem><para>The API to make calls to the arch specific kgdb implementation</para></listitem>
<listitem><para>The API to make calls to the arch-specific kgdb implementation</para></listitem>
<listitem><para>The logic to perform safe memory reads and writes to memory while using the debugger</para></listitem>
<listitem><para>A full implementation for software breakpoints unless overridden by the arch</para></listitem>
<listitem><para>The API to invoke either the kdb or kgdb frontend to the debug core.</para></listitem>
</itemizedlist>
</para>
</listitem>
<listitem><para>kgdb arch specific implementation</para>
<listitem><para>kgdb arch-specific implementation</para>
<para>
This implementation is generally found in arch/*/kernel/kgdb.c.
As an example, arch/x86/kernel/kgdb.c contains the specifics to
implement HW breakpoint as well as the initialization to
dynamically register and unregister for the trap handlers on
this architecture. The arch specific portion implements:
this architecture. The arch-specific portion implements:
<itemizedlist>
<listitem><para>contains an arch specific trap catcher which
<listitem><para>contains an arch-specific trap catcher which
invokes kgdb_handle_exception() to start kgdb about doing its
work</para></listitem>
<listitem><para>translation to and from gdb specific packet format to pt_regs</para></listitem>
@ -347,11 +659,35 @@
</itemizedlist>
</para>
</listitem>
<listitem><para>gdbstub frontend (aka kgdb)</para>
<para>The gdbstub is located in kernel/debug/gdbstub.c. It contains:</para>
<itemizedlist>
<listitem><para>All the logic to implement the gdb serial protocol</para></listitem>
</itemizedlist>
</listitem>
<listitem><para>kdb frontend</para>
<para>The kdb debugger shell is broken down into a number of
components. The kdb core is located in kernel/debug/kdb. There
are a number of helper functions in some of the other kernel
components to make it possible for kdb to examine and report
information about the kernel without taking locks that could
cause a kernel deadlock. The kdb core contains implements the following functionality.</para>
<itemizedlist>
<listitem><para>A simple shell</para></listitem>
<listitem><para>The kdb core command set</para></listitem>
<listitem><para>A registration API to register additional kdb shell commands.</para>
<para>A good example of a self-contained kdb module is the "ftdump" command for dumping the ftrace buffer. See: kernel/trace/trace_kdb.c</para></listitem>
<listitem><para>The implementation for kdb_printf() which
emits messages directly to I/O drivers, bypassing the kernel
log.</para></listitem>
<listitem><para>SW / HW breakpoint management for the kdb shell</para></listitem>
</itemizedlist>
</listitem>
<listitem><para>kgdb I/O driver</para>
<para>
Each kgdb I/O driver has to provide an implemenation for the following:
Each kgdb I/O driver has to provide an implementation for the following:
<itemizedlist>
<listitem><para>configuration via builtin or module</para></listitem>
<listitem><para>configuration via built-in or module</para></listitem>
<listitem><para>dynamic configuration and kgdb hook registration calls</para></listitem>
<listitem><para>read and write character interface</para></listitem>
<listitem><para>A cleanup handler for unconfiguring from the kgdb core</para></listitem>
@ -416,15 +752,15 @@
underlying low level to the hardware driver having "polling hooks"
which the to which the tty driver is attached. In the initial
implementation of kgdboc it the serial_core was changed to expose a
low level uart hook for doing polled mode reading and writing of a
low level UART hook for doing polled mode reading and writing of a
single character while in an atomic context. When kgdb makes an I/O
request to the debugger, kgdboc invokes a call back in the serial
core which in turn uses the call back in the uart driver. It is
certainly possible to extend kgdboc to work with non-uart based
core which in turn uses the call back in the UART driver. It is
certainly possible to extend kgdboc to work with non-UART based
consoles in the future.
</para>
<para>
When using kgdboc with a uart, the uart driver must implement two callbacks in the <constant>struct uart_ops</constant>. Example from drivers/8250.c:<programlisting>
When using kgdboc with a UART, the UART driver must implement two callbacks in the <constant>struct uart_ops</constant>. Example from drivers/8250.c:<programlisting>
#ifdef CONFIG_CONSOLE_POLL
.poll_get_char = serial8250_get_poll_char,
.poll_put_char = serial8250_put_poll_char,
@ -434,7 +770,7 @@
<constant>#ifdef CONFIG_CONSOLE_POLL</constant>, as shown above.
Keep in mind that polling hooks have to be implemented in such a way
that they can be called from an atomic context and have to restore
the state of the uart chip on return such that the system can return
the state of the UART chip on return such that the system can return
to normal when the debugger detaches. You need to be very careful
with any kind of lock you consider, because failing here is most
going to mean pressing the reset button.
@ -453,6 +789,10 @@
<itemizedlist>
<listitem><para>Jason Wessel<email>jason.wessel@windriver.com</email></para></listitem>
</itemizedlist>
In Jan 2010 this document was updated to include kdb.
<itemizedlist>
<listitem><para>Jason Wessel<email>jason.wessel@windriver.com</email></para></listitem>
</itemizedlist>
</para>
</chapter>
</book>

65
Documentation/DocBook/libata.tmpl
View File

@ -81,16 +81,14 @@ void (*port_disable) (struct ata_port *);
</programlisting>
<para>
Called from ata_bus_probe() and ata_bus_reset() error paths,
as well as when unregistering from the SCSI module (rmmod, hot
unplug).
Called from ata_bus_probe() error path, as well as when
unregistering from the SCSI module (rmmod, hot unplug).
This function should do whatever needs to be done to take the
port out of use. In most cases, ata_port_disable() can be used
as this hook.
</para>
<para>
Called from ata_bus_probe() on a failed probe.
Called from ata_bus_reset() on a failed bus reset.
Called from ata_scsi_release().
</para>
@ -107,10 +105,6 @@ void (*dev_config) (struct ata_port *, struct ata_device *);
issue of SET FEATURES - XFER MODE, and prior to operation.
</para>
<para>
Called by ata_device_add() after ata_dev_identify() determines
a device is present.
</para>
<para>
This entry may be specified as NULL in ata_port_operations.
</para>
@ -154,8 +148,8 @@ unsigned int (*mode_filter) (struct ata_port *, struct ata_device *, unsigned in
<sect2><title>Taskfile read/write</title>
<programlisting>
void (*tf_load) (struct ata_port *ap, struct ata_taskfile *tf);
void (*tf_read) (struct ata_port *ap, struct ata_taskfile *tf);
void (*sff_tf_load) (struct ata_port *ap, struct ata_taskfile *tf);
void (*sff_tf_read) (struct ata_port *ap, struct ata_taskfile *tf);
</programlisting>
<para>
@ -164,36 +158,35 @@ void (*tf_read) (struct ata_port *ap, struct ata_taskfile *tf);
hardware registers / DMA buffers, to obtain the current set of
taskfile register values.
Most drivers for taskfile-based hardware (PIO or MMIO) use
ata_tf_load() and ata_tf_read() for these hooks.
ata_sff_tf_load() and ata_sff_tf_read() for these hooks.
</para>
</sect2>
<sect2><title>PIO data read/write</title>
<programlisting>
void (*data_xfer) (struct ata_device *, unsigned char *, unsigned int, int);
void (*sff_data_xfer) (struct ata_device *, unsigned char *, unsigned int, int);
</programlisting>
<para>
All bmdma-style drivers must implement this hook. This is the low-level
operation that actually copies the data bytes during a PIO data
transfer.
Typically the driver
will choose one of ata_pio_data_xfer_noirq(), ata_pio_data_xfer(), or
ata_mmio_data_xfer().
Typically the driver will choose one of ata_sff_data_xfer_noirq(),
ata_sff_data_xfer(), or ata_sff_data_xfer32().
</para>
</sect2>
<sect2><title>ATA command execute</title>
<programlisting>
void (*exec_command)(struct ata_port *ap, struct ata_taskfile *tf);
void (*sff_exec_command)(struct ata_port *ap, struct ata_taskfile *tf);
</programlisting>
<para>
causes an ATA command, previously loaded with
->tf_load(), to be initiated in hardware.
Most drivers for taskfile-based hardware use ata_exec_command()
Most drivers for taskfile-based hardware use ata_sff_exec_command()
for this hook.
</para>
@ -218,8 +211,8 @@ command.
<sect2><title>Read specific ATA shadow registers</title>
<programlisting>
u8 (*check_status)(struct ata_port *ap);
u8 (*check_altstatus)(struct ata_port *ap);
u8 (*sff_check_status)(struct ata_port *ap);
u8 (*sff_check_altstatus)(struct ata_port *ap);
</programlisting>
<para>
@ -227,20 +220,26 @@ u8 (*check_altstatus)(struct ata_port *ap);
hardware. On some hardware, reading the Status register has
the side effect of clearing the interrupt condition.
Most drivers for taskfile-based hardware use
ata_check_status() for this hook.
ata_sff_check_status() for this hook.
</para>
</sect2>
<sect2><title>Write specific ATA shadow register</title>
<programlisting>
void (*sff_set_devctl)(struct ata_port *ap, u8 ctl);
</programlisting>
<para>
Note that because this is called from ata_device_add(), at
least a dummy function that clears device interrupts must be
provided for all drivers, even if the controller doesn't
actually have a taskfile status register.
Write the device control ATA shadow register to the hardware.
Most drivers don't need to define this.
</para>
</sect2>
<sect2><title>Select ATA device on bus</title>
<programlisting>
void (*dev_select)(struct ata_port *ap, unsigned int device);
void (*sff_dev_select)(struct ata_port *ap, unsigned int device);
</programlisting>
<para>
@ -251,9 +250,7 @@ void (*dev_select)(struct ata_port *ap, unsigned int device);
</para>
<para>
Most drivers for taskfile-based hardware use
ata_std_dev_select() for this hook. Controllers which do not
support second drives on a port (such as SATA contollers) will
use ata_noop_dev_select().
ata_sff_dev_select() for this hook.
</para>
</sect2>
@ -441,13 +438,13 @@ void (*irq_clear) (struct ata_port *);
to struct ata_host_set.
</para>
<para>
Most legacy IDE drivers use ata_interrupt() for the
Most legacy IDE drivers use ata_sff_interrupt() for the
irq_handler hook, which scans all ports in the host_set,
determines which queued command was active (if any), and calls
ata_host_intr(ap,qc).
ata_sff_host_intr(ap,qc).
</para>
<para>
Most legacy IDE drivers use ata_bmdma_irq_clear() for the
Most legacy IDE drivers use ata_sff_irq_clear() for the
irq_clear() hook, which simply clears the interrupt and error
flags in the DMA status register.
</para>
@ -490,16 +487,12 @@ void (*host_stop) (struct ata_host_set *host_set);
allocates space for a legacy IDE PRD table and returns.
</para>
<para>
->port_stop() is called after ->host_stop(). It's sole function
->port_stop() is called after ->host_stop(). Its sole function
is to release DMA/memory resources, now that they are no longer
actively being used. Many drivers also free driver-private
data from port at this time.
</para>
<para>
Many drivers use ata_port_stop() as this hook, which frees the
PRD table.
</para>
<para>
->host_stop() is called after all ->port_stop() calls
have completed. The hook must finalize hardware shutdown, release DMA
and other resources, etc.

11
Documentation/DocBook/media-entities.tmpl
View File

@ -17,6 +17,7 @@
<!ENTITY VIDIOC-DBG-G-REGISTER "<link linkend='vidioc-dbg-g-register'><constant>VIDIOC_DBG_G_REGISTER</constant></link>">
<!ENTITY VIDIOC-DBG-S-REGISTER "<link linkend='vidioc-dbg-g-register'><constant>VIDIOC_DBG_S_REGISTER</constant></link>">
<!ENTITY VIDIOC-DQBUF "<link linkend='vidioc-qbuf'><constant>VIDIOC_DQBUF</constant></link>">
<!ENTITY VIDIOC-DQEVENT "<link linkend='vidioc-dqevent'><constant>VIDIOC_DQEVENT</constant></link>">
<!ENTITY VIDIOC-ENCODER-CMD "<link linkend='vidioc-encoder-cmd'><constant>VIDIOC_ENCODER_CMD</constant></link>">
<!ENTITY VIDIOC-ENUMAUDIO "<link linkend='vidioc-enumaudio'><constant>VIDIOC_ENUMAUDIO</constant></link>">
<!ENTITY VIDIOC-ENUMAUDOUT "<link linkend='vidioc-enumaudioout'><constant>VIDIOC_ENUMAUDOUT</constant></link>">
@ -60,6 +61,7 @@
<!ENTITY VIDIOC-REQBUFS "<link linkend='vidioc-reqbufs'><constant>VIDIOC_REQBUFS</constant></link>">
<!ENTITY VIDIOC-STREAMOFF "<link linkend='vidioc-streamon'><constant>VIDIOC_STREAMOFF</constant></link>">
<!ENTITY VIDIOC-STREAMON "<link linkend='vidioc-streamon'><constant>VIDIOC_STREAMON</constant></link>">
<!ENTITY VIDIOC-SUBSCRIBE-EVENT "<link linkend='vidioc-subscribe-event'><constant>VIDIOC_SUBSCRIBE_EVENT</constant></link>">
<!ENTITY VIDIOC-S-AUDIO "<link linkend='vidioc-g-audio'><constant>VIDIOC_S_AUDIO</constant></link>">
<!ENTITY VIDIOC-S-AUDOUT "<link linkend='vidioc-g-audioout'><constant>VIDIOC_S_AUDOUT</constant></link>">
<!ENTITY VIDIOC-S-CROP "<link linkend='vidioc-g-crop'><constant>VIDIOC_S_CROP</constant></link>">
@ -83,6 +85,7 @@
<!ENTITY VIDIOC-TRY-ENCODER-CMD "<link linkend='vidioc-encoder-cmd'><constant>VIDIOC_TRY_ENCODER_CMD</constant></link>">
<!ENTITY VIDIOC-TRY-EXT-CTRLS "<link linkend='vidioc-g-ext-ctrls'><constant>VIDIOC_TRY_EXT_CTRLS</constant></link>">
<!ENTITY VIDIOC-TRY-FMT "<link linkend='vidioc-g-fmt'><constant>VIDIOC_TRY_FMT</constant></link>">
<!ENTITY VIDIOC-UNSUBSCRIBE-EVENT "<link linkend='vidioc-subscribe-event'><constant>VIDIOC_UNSUBSCRIBE_EVENT</constant></link>">
<!-- Types -->
<!ENTITY v4l2-std-id "<link linkend='v4l2-std-id'>v4l2_std_id</link>">
@ -141,6 +144,9 @@
<!ENTITY v4l2-enc-idx "struct&nbsp;<link linkend='v4l2-enc-idx'>v4l2_enc_idx</link>">
<!ENTITY v4l2-enc-idx-entry "struct&nbsp;<link linkend='v4l2-enc-idx-entry'>v4l2_enc_idx_entry</link>">
<!ENTITY v4l2-encoder-cmd "struct&nbsp;<link linkend='v4l2-encoder-cmd'>v4l2_encoder_cmd</link>">
<!ENTITY v4l2-event "struct&nbsp;<link linkend='v4l2-event'>v4l2_event</link>">
<!ENTITY v4l2-event-subscription "struct&nbsp;<link linkend='v4l2-event-subscription'>v4l2_event_subscription</link>">
<!ENTITY v4l2-event-vsync "struct&nbsp;<link linkend='v4l2-event-vsync'>v4l2_event_vsync</link>">
<!ENTITY v4l2-ext-control "struct&nbsp;<link linkend='v4l2-ext-control'>v4l2_ext_control</link>">
<!ENTITY v4l2-ext-controls "struct&nbsp;<link linkend='v4l2-ext-controls'>v4l2_ext_controls</link>">
<!ENTITY v4l2-fmtdesc "struct&nbsp;<link linkend='v4l2-fmtdesc'>v4l2_fmtdesc</link>">
@ -200,6 +206,7 @@
<!ENTITY sub-controls SYSTEM "v4l/controls.xml">
<!ENTITY sub-dev-capture SYSTEM "v4l/dev-capture.xml">
<!ENTITY sub-dev-codec SYSTEM "v4l/dev-codec.xml">
<!ENTITY sub-dev-event SYSTEM "v4l/dev-event.xml">
<!ENTITY sub-dev-effect SYSTEM "v4l/dev-effect.xml">
<!ENTITY sub-dev-osd SYSTEM "v4l/dev-osd.xml">
<!ENTITY sub-dev-output SYSTEM "v4l/dev-output.xml">
@ -292,6 +299,8 @@
<!ENTITY sub-v4l2grab-c SYSTEM "v4l/v4l2grab.c.xml">
<!ENTITY sub-videodev2-h SYSTEM "v4l/videodev2.h.xml">
<!ENTITY sub-v4l2 SYSTEM "v4l/v4l2.xml">
<!ENTITY sub-dqevent SYSTEM "v4l/vidioc-dqevent.xml">
<!ENTITY sub-subscribe-event SYSTEM "v4l/vidioc-subscribe-event.xml">
<!ENTITY sub-intro SYSTEM "dvb/intro.xml">
<!ENTITY sub-frontend SYSTEM "dvb/frontend.xml">
<!ENTITY sub-dvbproperty SYSTEM "dvb/dvbproperty.xml">
@ -381,3 +390,5 @@
<!ENTITY reqbufs SYSTEM "v4l/vidioc-reqbufs.xml">
<!ENTITY s-hw-freq-seek SYSTEM "v4l/vidioc-s-hw-freq-seek.xml">
<!ENTITY streamon SYSTEM "v4l/vidioc-streamon.xml">
<!ENTITY dqevent SYSTEM "v4l/vidioc-dqevent.xml">
<!ENTITY subscribe_event SYSTEM "v4l/vidioc-subscribe-event.xml">

10
Documentation/DocBook/sh.tmpl
View File

@ -19,13 +19,17 @@
</authorgroup>
<copyright>
<year>2008</year>
<year>2008-2010</year>
<holder>Paul Mundt</holder>
</copyright>
<copyright>
<year>2008</year>
<year>2008-2010</year>
<holder>Renesas Technology Corp.</holder>
</copyright>
<copyright>
<year>2010</year>
<holder>Renesas Electronics Corp.</holder>
</copyright>
<legalnotice>
<para>
@ -77,7 +81,7 @@
</chapter>
<chapter id="clk">
<title>Clock Framework Extensions</title>
!Iarch/sh/include/asm/clock.h
!Iinclude/linux/sh_clk.h
</chapter>
<chapter id="mach">
<title>Machine Specific Interfaces</title>

130
Documentation/DocBook/v4l/compat.xml
View File

@ -2332,15 +2332,26 @@ more information.</para>
</listitem>
</orderedlist>
</section>
</section>
<section>
<title>V4L2 in Linux 2.6.34</title>
<orderedlist>
<listitem>
<para>Added
<constant>V4L2_CID_IRIS_ABSOLUTE</constant> and
<constant>V4L2_CID_IRIS_RELATIVE</constant> controls to the
<link linkend="camera-controls">Camera controls class</link>.
</para>
</listitem>
</orderedlist>
</section>
<section id="other">
<title>Relation of V4L2 to other Linux multimedia APIs</title>
<section id="other">
<title>Relation of V4L2 to other Linux multimedia APIs</title>
<section id="xvideo">
<title>X Video Extension</title>
<section id="xvideo">
<title>X Video Extension</title>
<para>The X Video Extension (abbreviated XVideo or just Xv) is
<para>The X Video Extension (abbreviated XVideo or just Xv) is
an extension of the X Window system, implemented for example by the
XFree86 project. Its scope is similar to V4L2, an API to video capture
and output devices for X clients. Xv allows applications to display
@ -2351,7 +2362,7 @@ capture or output still images in XPixmaps<footnote>
extension available across many operating systems and
architectures.</para>
<para>Because the driver is embedded into the X server Xv has a
<para>Because the driver is embedded into the X server Xv has a
number of advantages over the V4L2 <link linkend="overlay">video
overlay interface</link>. The driver can easily determine the overlay
target, &ie; visible graphics memory or off-screen buffers for a
@ -2360,16 +2371,16 @@ overlay, scaling or color-keying, or the clipping functions of the
video capture hardware, always in sync with drawing operations or
windows moving or changing their stacking order.</para>
<para>To combine the advantages of Xv and V4L a special Xv
<para>To combine the advantages of Xv and V4L a special Xv
driver exists in XFree86 and XOrg, just programming any overlay capable
Video4Linux device it finds. To enable it
<filename>/etc/X11/XF86Config</filename> must contain these lines:</para>
<para><screen>
<para><screen>
Section "Module"
Load "v4l"
EndSection</screen></para>
<para>As of XFree86 4.2 this driver still supports only V4L
<para>As of XFree86 4.2 this driver still supports only V4L
ioctls, however it should work just fine with all V4L2 devices through
the V4L2 backward-compatibility layer. Since V4L2 permits multiple
opens it is possible (if supported by the V4L2 driver) to capture
@ -2377,83 +2388,84 @@ video while an X client requested video overlay. Restrictions of
simultaneous capturing and overlay are discussed in <xref
linkend="overlay" /> apply.</para>
<para>Only marginally related to V4L2, XFree86 extended Xv to
<para>Only marginally related to V4L2, XFree86 extended Xv to
support hardware YUV to RGB conversion and scaling for faster video
playback, and added an interface to MPEG-2 decoding hardware. This API
is useful to display images captured with V4L2 devices.</para>
</section>
</section>
<section>
<title>Digital Video</title>
<section>
<title>Digital Video</title>
<para>V4L2 does not support digital terrestrial, cable or
<para>V4L2 does not support digital terrestrial, cable or
satellite broadcast. A separate project aiming at digital receivers
exists. You can find its homepage at <ulink
url="http://linuxtv.org">http://linuxtv.org</ulink>. The Linux DVB API
has no connection to the V4L2 API except that drivers for hybrid
hardware may support both.</para>
</section>
<section>
<title>Audio Interfaces</title>
<para>[to do - OSS/ALSA]</para>
</section>
</section>
<section>
<title>Audio Interfaces</title>
<section id="experimental">
<title>Experimental API Elements</title>
<para>[to do - OSS/ALSA]</para>
</section>
</section>
<section id="experimental">
<title>Experimental API Elements</title>
<para>The following V4L2 API elements are currently experimental
<para>The following V4L2 API elements are currently experimental
and may change in the future.</para>
<itemizedlist>
<listitem>
<para>Video Output Overlay (OSD) Interface, <xref
<itemizedlist>
<listitem>
<para>Video Output Overlay (OSD) Interface, <xref
linkend="osd" />.</para>
</listitem>
</listitem>
<listitem>
<para><constant>V4L2_BUF_TYPE_VIDEO_OUTPUT_OVERLAY</constant>,
<para><constant>V4L2_BUF_TYPE_VIDEO_OUTPUT_OVERLAY</constant>,
&v4l2-buf-type;, <xref linkend="v4l2-buf-type" />.</para>
</listitem>
<listitem>
<para><constant>V4L2_CAP_VIDEO_OUTPUT_OVERLAY</constant>,
</listitem>
<listitem>
<para><constant>V4L2_CAP_VIDEO_OUTPUT_OVERLAY</constant>,
&VIDIOC-QUERYCAP; ioctl, <xref linkend="device-capabilities" />.</para>
</listitem>
<listitem>
<para>&VIDIOC-ENUM-FRAMESIZES; and
</listitem>
<listitem>
<para>&VIDIOC-ENUM-FRAMESIZES; and
&VIDIOC-ENUM-FRAMEINTERVALS; ioctls.</para>
</listitem>
<listitem>
<para>&VIDIOC-G-ENC-INDEX; ioctl.</para>
</listitem>
<listitem>
<para>&VIDIOC-ENCODER-CMD; and &VIDIOC-TRY-ENCODER-CMD;
</listitem>
<listitem>
<para>&VIDIOC-G-ENC-INDEX; ioctl.</para>
</listitem>
<listitem>
<para>&VIDIOC-ENCODER-CMD; and &VIDIOC-TRY-ENCODER-CMD;
ioctls.</para>
</listitem>
<listitem>
<para>&VIDIOC-DBG-G-REGISTER; and &VIDIOC-DBG-S-REGISTER;
</listitem>
<listitem>
<para>&VIDIOC-DBG-G-REGISTER; and &VIDIOC-DBG-S-REGISTER;
ioctls.</para>
</listitem>
<listitem>
<para>&VIDIOC-DBG-G-CHIP-IDENT; ioctl.</para>
</listitem>
</itemizedlist>
</section>
</listitem>
<listitem>
<para>&VIDIOC-DBG-G-CHIP-IDENT; ioctl.</para>
</listitem>
</itemizedlist>
</section>
<section id="obsolete">
<title>Obsolete API Elements</title>
<section id="obsolete">
<title>Obsolete API Elements</title>
<para>The following V4L2 API elements were superseded by new
<para>The following V4L2 API elements were superseded by new
interfaces and should not be implemented in new drivers.</para>
<itemizedlist>
<listitem>
<para><constant>VIDIOC_G_MPEGCOMP</constant> and
<itemizedlist>
<listitem>
<para><constant>VIDIOC_G_MPEGCOMP</constant> and
<constant>VIDIOC_S_MPEGCOMP</constant> ioctls. Use Extended Controls,
<xref linkend="extended-controls" />.</para>
</listitem>
</itemizedlist>
</listitem>
</itemizedlist>
</section>
</section>
<!--

36
Documentation/DocBook/v4l/controls.xml
View File

@ -266,6 +266,12 @@ minimum value disables backlight compensation.</entry>
<entry>boolean</entry>
<entry>Chroma automatic gain control.</entry>
</row>
<row>
<entry><constant>V4L2_CID_CHROMA_GAIN</constant></entry>
<entry>integer</entry>
<entry>Adjusts the Chroma gain control (for use when chroma AGC
is disabled).</entry>
</row>
<row>
<entry><constant>V4L2_CID_COLOR_KILLER</constant></entry>
<entry>boolean</entry>
@ -277,8 +283,15 @@ minimum value disables backlight compensation.</entry>
<entry>Selects a color effect. Possible values for
<constant>enum v4l2_colorfx</constant> are:
<constant>V4L2_COLORFX_NONE</constant> (0),
<constant>V4L2_COLORFX_BW</constant> (1) and
<constant>V4L2_COLORFX_SEPIA</constant> (2).</entry>
<constant>V4L2_COLORFX_BW</constant> (1),
<constant>V4L2_COLORFX_SEPIA</constant> (2),
<constant>V4L2_COLORFX_NEGATIVE</constant> (3),
<constant>V4L2_COLORFX_EMBOSS</constant> (4),
<constant>V4L2_COLORFX_SKETCH</constant> (5),
<constant>V4L2_COLORFX_SKY_BLUE</constant> (6),
<constant>V4L2_COLORFX_GRASS_GREEN</constant> (7),
<constant>V4L2_COLORFX_SKIN_WHITEN</constant> (8) and
<constant>V4L2_COLORFX_VIVID</constant> (9).</entry>
</row>
<row>
<entry><constant>V4L2_CID_ROTATE</constant></entry>
@ -1824,6 +1837,25 @@ wide-angle direction. The zoom speed unit is driver-specific.</entry>
</row>
<row><entry></entry></row>
<row>
<entry spanname="id"><constant>V4L2_CID_IRIS_ABSOLUTE</constant>&nbsp;</entry>
<entry>integer</entry>
</row><row><entry spanname="descr">This control sets the
camera's aperture to the specified value. The unit is undefined.
Larger values open the iris wider, smaller values close it.</entry>
</row>
<row><entry></entry></row>
<row>
<entry spanname="id"><constant>V4L2_CID_IRIS_RELATIVE</constant>&nbsp;</entry>
<entry>integer</entry>
</row><row><entry spanname="descr">This control modifies the
camera's aperture by the specified amount. The unit is undefined.
Positive values open the iris one step further, negative values close
it one step further. This is a write-only control.</entry>
</row>
<row><entry></entry></row>
<row>
<entry spanname="id"><constant>V4L2_CID_PRIVACY</constant>&nbsp;</entry>
<entry>boolean</entry>

31
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@ -0,0 +1,31 @@
<title>Event Interface</title>
<para>The V4L2 event interface provides means for user to get
immediately notified on certain conditions taking place on a device.
This might include start of frame or loss of signal events, for
example.
</para>
<para>To receive events, the events the user is interested in first must
be subscribed using the &VIDIOC-SUBSCRIBE-EVENT; ioctl. Once an event is
subscribed, the events of subscribed types are dequeueable using the
&VIDIOC-DQEVENT; ioctl. Events may be unsubscribed using
VIDIOC_UNSUBSCRIBE_EVENT ioctl. The special event type V4L2_EVENT_ALL may
be used to unsubscribe all the events the driver supports.</para>
<para>The event subscriptions and event queues are specific to file
handles. Subscribing an event on one file handle does not affect
other file handles.
</para>
<para>The information on dequeueable events is obtained by using select or
poll system calls on video devices. The V4L2 events use POLLPRI events on
poll system call and exceptions on select system call. </para>
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18
Documentation/DocBook/v4l/io.xml
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@ -701,6 +701,16 @@ buffer cannot be on both queues at the same time, the
They can be both cleared however, then the buffer is in "dequeued"
state, in the application domain to say so.</entry>
</row>
<row>
<entry><constant>V4L2_BUF_FLAG_ERROR</constant></entry>
<entry>0x0040</entry>
<entry>When this flag is set, the buffer has been dequeued
successfully, although the data might have been corrupted.
This is recoverable, streaming may continue as normal and
the buffer may be reused normally.
Drivers set this flag when the <constant>VIDIOC_DQBUF</constant>
ioctl is called.</entry>
</row>
<row>
<entry><constant>V4L2_BUF_FLAG_KEYFRAME</constant></entry>
<entry>0x0008</entry>
@ -918,8 +928,8 @@ order</emphasis>.</para>
<para>When the driver provides or accepts images field by field
rather than interleaved, it is also important applications understand
how the fields combine to frames. We distinguish between top and
bottom fields, the <emphasis>spatial order</emphasis>: The first line
how the fields combine to frames. We distinguish between top (aka odd) and
bottom (aka even) fields, the <emphasis>spatial order</emphasis>: The first line
of the top field is the first line of an interlaced frame, the first
line of the bottom field is the second line of that frame.</para>
@ -972,12 +982,12 @@ between <constant>V4L2_FIELD_TOP</constant> and
<row>
<entry><constant>V4L2_FIELD_TOP</constant></entry>
<entry>2</entry>
<entry>Images consist of the top field only.</entry>
<entry>Images consist of the top (aka odd) field only.</entry>
</row>
<row>
<entry><constant>V4L2_FIELD_BOTTOM</constant></entry>
<entry>3</entry>
<entry>Images consist of the bottom field only.
<entry>Images consist of the bottom (aka even) field only.
Applications may wish to prevent a device from capturing interlaced
images because they will have "comb" or "feathering" artefacts around
moving objects.</entry>

12
Documentation/DocBook/v4l/pixfmt.xml
View File

@ -792,6 +792,18 @@ http://www.thedirks.org/winnov/</ulink></para></entry>
<entry>'YYUV'</entry>
<entry>unknown</entry>
</row>
<row id="V4L2-PIX-FMT-Y4">
<entry><constant>V4L2_PIX_FMT_Y4</constant></entry>
<entry>'Y04 '</entry>
<entry>Old 4-bit greyscale format. Only the least significant 4 bits of each byte are used,
the other bits are set to 0.</entry>
</row>
<row id="V4L2-PIX-FMT-Y6">
<entry><constant>V4L2_PIX_FMT_Y6</constant></entry>
<entry>'Y06 '</entry>
<entry>Old 6-bit greyscale format. Only the least significant 6 bits of each byte are used,
the other bits are set to 0.</entry>
</row>
</tbody>
</tgroup>
</table>

3
Documentation/DocBook/v4l/v4l2.xml
View File

@ -401,6 +401,7 @@ and discussions on the V4L mailing list.</revremark>
<section id="ttx"> &sub-dev-teletext; </section>
<section id="radio"> &sub-dev-radio; </section>
<section id="rds"> &sub-dev-rds; </section>
<section id="event"> &sub-dev-event; </section>
</chapter>
<chapter id="driver">
@ -426,6 +427,7 @@ and discussions on the V4L mailing list.</revremark>
&sub-cropcap;
&sub-dbg-g-chip-ident;
&sub-dbg-g-register;
&sub-dqevent;
&sub-encoder-cmd;
&sub-enumaudio;
&sub-enumaudioout;
@ -467,6 +469,7 @@ and discussions on the V4L mailing list.</revremark>
&sub-reqbufs;
&sub-s-hw-freq-seek;
&sub-streamon;
&sub-subscribe-event;
<!-- End of ioctls. -->
&sub-mmap;
&sub-munmap;

10
Documentation/DocBook/v4l/videodev2.h.xml
View File

@ -1018,6 +1018,13 @@ enum <link linkend="v4l2-colorfx">v4l2_colorfx</link> {
V4L2_COLORFX_NONE = 0,
V4L2_COLORFX_BW = 1,
V4L2_COLORFX_SEPIA = 2,
V4L2_COLORFX_NEGATIVE = 3,
V4L2_COLORFX_EMBOSS = 4,
V4L2_COLORFX_SKETCH = 5,
V4L2_COLORFX_SKY_BLUE = 6,
V4L2_COLORFX_GRASS_GREEN = 7,
V4L2_COLORFX_SKIN_WHITEN = 8,
V4L2_COLORFX_VIVID = 9.
};
#define V4L2_CID_AUTOBRIGHTNESS (V4L2_CID_BASE+32)
#define V4L2_CID_BAND_STOP_FILTER (V4L2_CID_BASE+33)
@ -1271,6 +1278,9 @@ enum <link linkend="v4l2-exposure-auto-type">v4l2_exposure_auto_type</link> {
#define V4L2_CID_PRIVACY (V4L2_CID_CAMERA_CLASS_BASE+16)
#define V4L2_CID_IRIS_ABSOLUTE (V4L2_CID_CAMERA_CLASS_BASE+17)
#define V4L2_CID_IRIS_RELATIVE (V4L2_CID_CAMERA_CLASS_BASE+18)
/* FM Modulator class control IDs */
#define V4L2_CID_FM_TX_CLASS_BASE (V4L2_CTRL_CLASS_FM_TX | 0x900)
#define V4L2_CID_FM_TX_CLASS (V4L2_CTRL_CLASS_FM_TX | 1)

131
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@ -0,0 +1,131 @@
<refentry id="vidioc-dqevent">
<refmeta>
<refentrytitle>ioctl VIDIOC_DQEVENT</refentrytitle>
&manvol;
</refmeta>
<refnamediv>
<refname>VIDIOC_DQEVENT</refname>
<refpurpose>Dequeue event</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcprototype>
<funcdef>int <function>ioctl</function></funcdef>
<paramdef>int <parameter>fd</parameter></paramdef>
<paramdef>int <parameter>request</parameter></paramdef>
<paramdef>struct v4l2_event
*<parameter>argp</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>fd</parameter></term>
<listitem>
<para>&fd;</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>request</parameter></term>
<listitem>
<para>VIDIOC_DQEVENT</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>argp</parameter></term>
<listitem>
<para></para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>Dequeue an event from a video device. No input is required
for this ioctl. All the fields of the &v4l2-event; structure are
filled by the driver. The file handle will also receive exceptions
which the application may get by e.g. using the select system
call.</para>
<table frame="none" pgwide="1" id="v4l2-event">
<title>struct <structname>v4l2_event</structname></title>
<tgroup cols="4">
&cs-str;
<tbody valign="top">
<row>
<entry>__u32</entry>
<entry><structfield>type</structfield></entry>
<entry></entry>
<entry>Type of the event.</entry>
</row>
<row>
<entry>union</entry>
<entry><structfield>u</structfield></entry>
<entry></entry>
<entry></entry>
</row>
<row>
<entry></entry>
<entry>&v4l2-event-vsync;</entry>
<entry><structfield>vsync</structfield></entry>
<entry>Event data for event V4L2_EVENT_VSYNC.
</entry>
</row>
<row>
<entry></entry>
<entry>__u8</entry>
<entry><structfield>data</structfield>[64]</entry>
<entry>Event data. Defined by the event type. The union
should be used to define easily accessible type for
events.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>pending</structfield></entry>
<entry></entry>
<entry>Number of pending events excluding this one.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>sequence</structfield></entry>
<entry></entry>
<entry>Event sequence number. The sequence number is
incremented for every subscribed event that takes place.
If sequence numbers are not contiguous it means that
events have been lost.
</entry>
</row>
<row>
<entry>struct timespec</entry>
<entry><structfield>timestamp</structfield></entry>
<entry></entry>
<entry>Event timestamp.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>reserved</structfield>[9]</entry>
<entry></entry>
<entry>Reserved for future extensions. Drivers must set
the array to zero.</entry>
</row>
</tbody>
</tgroup>
</table>
</refsect1>
</refentry>
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2
Documentation/DocBook/v4l/vidioc-enuminput.xml
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@ -283,7 +283,7 @@ input/output interface to linux-media@vger.kernel.org on 19 Oct 2009.
<entry>This input supports setting DV presets by using VIDIOC_S_DV_PRESET.</entry>
</row>
<row>
<entry><constant>V4L2_OUT_CAP_CUSTOM_TIMINGS</constant></entry>
<entry><constant>V4L2_IN_CAP_CUSTOM_TIMINGS</constant></entry>
<entry>0x00000002</entry>
<entry>This input supports setting custom video timings by using VIDIOC_S_DV_TIMINGS.</entry>
</row>

14
Documentation/DocBook/v4l/vidioc-qbuf.xml
View File

@ -111,7 +111,11 @@ from the driver's outgoing queue. They just set the
and <structfield>reserved</structfield>
fields of a &v4l2-buffer; as above, when <constant>VIDIOC_DQBUF</constant>
is called with a pointer to this structure the driver fills the
remaining fields or returns an error code.</para>
remaining fields or returns an error code. The driver may also set
<constant>V4L2_BUF_FLAG_ERROR</constant> in the <structfield>flags</structfield>
field. It indicates a non-critical (recoverable) streaming error. In such case
the application may continue as normal, but should be aware that data in the
dequeued buffer might be corrupted.</para>
<para>By default <constant>VIDIOC_DQBUF</constant> blocks when no
buffer is in the outgoing queue. When the
@ -158,7 +162,13 @@ enqueue a user pointer buffer.</para>
<para><constant>VIDIOC_DQBUF</constant> failed due to an
internal error. Can also indicate temporary problems like signal
loss. Note the driver might dequeue an (empty) buffer despite
returning an error, or even stop capturing.</para>
returning an error, or even stop capturing. Reusing such buffer may be unsafe
though and its details (e.g. <structfield>index</structfield>) may not be
returned either. It is recommended that drivers indicate recoverable errors
by setting the <constant>V4L2_BUF_FLAG_ERROR</constant> and returning 0 instead.
In that case the application should be able to safely reuse the buffer and
continue streaming.
</para>
</listitem>
</varlistentry>
</variablelist>

2
Documentation/DocBook/v4l/vidioc-queryctrl.xml
View File

@ -325,7 +325,7 @@ should be part of the control documentation.</entry>
<entry>n/a</entry>
<entry>This is not a control. When
<constant>VIDIOC_QUERYCTRL</constant> is called with a control ID
equal to a control class code (see <xref linkend="ctrl-class" />), the
equal to a control class code (see <xref linkend="ctrl-class" />) + 1, the
ioctl returns the name of the control class and this control type.
Older drivers which do not support this feature return an
&EINVAL;.</entry>

2
Documentation/DocBook/v4l/vidioc-reqbufs.xml
View File

@ -61,7 +61,7 @@ fields of the <structname>v4l2_requestbuffers</structname> structure.
They set the <structfield>type</structfield> field to the respective
stream or buffer type, the <structfield>count</structfield> field to
the desired number of buffers, <structfield>memory</structfield>
must be set to the requested I/O method and the reserved array
must be set to the requested I/O method and the <structfield>reserved</structfield> array
must be zeroed. When the ioctl
is called with a pointer to this structure the driver will attempt to allocate
the requested number of buffers and it stores the actual number

133
Documentation/DocBook/v4l/vidioc-subscribe-event.xml Normal file
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@ -0,0 +1,133 @@
<refentry id="vidioc-subscribe-event">
<refmeta>
<refentrytitle>ioctl VIDIOC_SUBSCRIBE_EVENT, VIDIOC_UNSUBSCRIBE_EVENT</refentrytitle>
&manvol;
</refmeta>
<refnamediv>
<refname>VIDIOC_SUBSCRIBE_EVENT, VIDIOC_UNSUBSCRIBE_EVENT</refname>
<refpurpose>Subscribe or unsubscribe event</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcprototype>
<funcdef>int <function>ioctl</function></funcdef>
<paramdef>int <parameter>fd</parameter></paramdef>
<paramdef>int <parameter>request</parameter></paramdef>
<paramdef>struct v4l2_event_subscription
*<parameter>argp</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>fd</parameter></term>
<listitem>
<para>&fd;</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>request</parameter></term>
<listitem>
<para>VIDIOC_SUBSCRIBE_EVENT, VIDIOC_UNSUBSCRIBE_EVENT</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>argp</parameter></term>
<listitem>
<para></para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>Subscribe or unsubscribe V4L2 event. Subscribed events are
dequeued by using the &VIDIOC-DQEVENT; ioctl.</para>
<table frame="none" pgwide="1" id="v4l2-event-subscription">
<title>struct <structname>v4l2_event_subscription</structname></title>
<tgroup cols="3">
&cs-str;
<tbody valign="top">
<row>
<entry>__u32</entry>
<entry><structfield>type</structfield></entry>
<entry>Type of the event.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>reserved</structfield>[7]</entry>
<entry>Reserved for future extensions. Drivers and applications
must set the array to zero.</entry>
</row>
</tbody>
</tgroup>
</table>
<table frame="none" pgwide="1" id="event-type">
<title>Event Types</title>
<tgroup cols="3">
&cs-def;
<tbody valign="top">
<row>
<entry><constant>V4L2_EVENT_ALL</constant></entry>
<entry>0</entry>
<entry>All events. V4L2_EVENT_ALL is valid only for
VIDIOC_UNSUBSCRIBE_EVENT for unsubscribing all events at once.
</entry>
</row>
<row>
<entry><constant>V4L2_EVENT_VSYNC</constant></entry>
<entry>1</entry>
<entry>This event is triggered on the vertical sync.
This event has &v4l2-event-vsync; associated with it.
</entry>
</row>
<row>
<entry><constant>V4L2_EVENT_EOS</constant></entry>
<entry>2</entry>
<entry>This event is triggered when the end of a stream is reached.
This is typically used with MPEG decoders to report to the application
when the last of the MPEG stream has been decoded.
</entry>
</row>
<row>
<entry><constant>V4L2_EVENT_PRIVATE_START</constant></entry>
<entry>0x08000000</entry>
<entry>Base event number for driver-private events.</entry>
</row>
</tbody>
</tgroup>
</table>
<table frame="none" pgwide="1" id="v4l2-event-vsync">
<title>struct <structname>v4l2_event_vsync</structname></title>
<tgroup cols="3">
&cs-str;
<tbody valign="top">
<row>
<entry>__u8</entry>
<entry><structfield>field</structfield></entry>
<entry>The upcoming field. See &v4l2-field;.</entry>
</row>
</tbody>
</tgroup>
</table>
</refsect1>
</refentry>
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27
Documentation/DocBook/writing-an-alsa-driver.tmpl
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@ -5518,34 +5518,41 @@ struct _snd_pcm_runtime {
]]>
</programlisting>
</informalexample>
For the raw data, <structfield>size</structfield> field must be
set properly. This specifies the maximum size of the proc file access.
</para>
<para>
The callback is much more complicated than the text-file
version. You need to use a low-level I/O functions such as
The read/write callbacks of raw mode are more direct than the text mode.
You need to use a low-level I/O functions such as
<function>copy_from/to_user()</function> to transfer the
data.
<informalexample>
<programlisting>
<![CDATA[
static long my_file_io_read(struct snd_info_entry *entry,
static ssize_t my_file_io_read(struct snd_info_entry *entry,
void *file_private_data,
struct file *file,
char *buf,
unsigned long count,
unsigned long pos)
size_t count,
loff_t pos)
{
long size = count;
if (pos + size > local_max_size)
size = local_max_size - pos;
if (copy_to_user(buf, local_data + pos, size))
if (copy_to_user(buf, local_data + pos, count))
return -EFAULT;
return size;
return count;
}
]]>
</programlisting>
</informalexample>
If the size of the info entry has been set up properly,
<structfield>count</structfield> and <structfield>pos</structfield> are
guaranteed to fit within 0 and the given size.
You don't have to check the range in the callbacks unless any
other condition is required.
</para>
</chapter>

2
Documentation/DocBook/writing_usb_driver.tmpl
View File

@ -342,7 +342,7 @@ static inline void skel_delete (struct usb_skel *dev)
{
kfree (dev->bulk_in_buffer);
if (dev->bulk_out_buffer != NULL)
usb_buffer_free (dev->udev, dev->bulk_out_size,
usb_free_coherent (dev->udev, dev->bulk_out_size,
dev->bulk_out_buffer,
dev->write_urb->transfer_dma);
usb_free_urb (dev->write_urb);

4
Documentation/PCI/pci-error-recovery.txt
View File

@ -216,7 +216,7 @@ The driver should return one of the following result codes:
- PCI_ERS_RESULT_NEED_RESET
Driver returns this if it thinks the device is not
recoverable in it's current state and it needs a slot
recoverable in its current state and it needs a slot
reset to proceed.
- PCI_ERS_RESULT_DISCONNECT
@ -241,7 +241,7 @@ in working condition.
The driver is not supposed to restart normal driver I/O operations
at this point. It should limit itself to "probing" the device to
check it's recoverability status. If all is right, then the platform
check its recoverability status. If all is right, then the platform
will call resume() once all drivers have ack'd link_reset().
Result codes:

92
Documentation/RCU/stallwarn.txt
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@ -3,35 +3,79 @@ Using RCU's CPU Stall Detector
The CONFIG_RCU_CPU_STALL_DETECTOR kernel config parameter enables
RCU's CPU stall detector, which detects conditions that unduly delay
RCU grace periods. The stall detector's idea of what constitutes
"unduly delayed" is controlled by a pair of C preprocessor macros:
"unduly delayed" is controlled by a set of C preprocessor macros:
RCU_SECONDS_TILL_STALL_CHECK
This macro defines the period of time that RCU will wait from
the beginning of a grace period until it issues an RCU CPU
stall warning. It is normally ten seconds.
stall warning. This time period is normally ten seconds.
RCU_SECONDS_TILL_STALL_RECHECK
This macro defines the period of time that RCU will wait after
issuing a stall warning until it issues another stall warning.
It is normally set to thirty seconds.
issuing a stall warning until it issues another stall warning
for the same stall. This time period is normally set to thirty
seconds.
RCU_STALL_RAT_DELAY
The CPU stall detector tries to make the offending CPU rat on itself,
as this often gives better-quality stack traces. However, if
the offending CPU does not detect its own stall in the number
of jiffies specified by RCU_STALL_RAT_DELAY, then other CPUs will
complain. This is normally set to two jiffies.
The CPU stall detector tries to make the offending CPU print its
own warnings, as this often gives better-quality stack traces.
However, if the offending CPU does not detect its own stall in
the number of jiffies specified by RCU_STALL_RAT_DELAY, then
some other CPU will complain. This delay is normally set to
two jiffies.
The following problems can result in an RCU CPU stall warning:
When a CPU detects that it is stalling, it will print a message similar
to the following:
INFO: rcu_sched_state detected stall on CPU 5 (t=2500 jiffies)
This message indicates that CPU 5 detected that it was causing a stall,
and that the stall was affecting RCU-sched. This message will normally be
followed by a stack dump of the offending CPU. On TREE_RCU kernel builds,
RCU and RCU-sched are implemented by the same underlying mechanism,
while on TREE_PREEMPT_RCU kernel builds, RCU is instead implemented
by rcu_preempt_state.
On the other hand, if the offending CPU fails to print out a stall-warning
message quickly enough, some other CPU will print a message similar to
the following:
INFO: rcu_bh_state detected stalls on CPUs/tasks: { 3 5 } (detected by 2, 2502 jiffies)
This message indicates that CPU 2 detected that CPUs 3 and 5 were both
causing stalls, and that the stall was affecting RCU-bh. This message
will normally be followed by stack dumps for each CPU. Please note that
TREE_PREEMPT_RCU builds can be stalled by tasks as well as by CPUs,
and that the tasks will be indicated by PID, for example, "P3421".
It is even possible for a rcu_preempt_state stall to be caused by both
CPUs -and- tasks, in which case the offending CPUs and tasks will all
be called out in the list.
Finally, if the grace period ends just as the stall warning starts
printing, there will be a spurious stall-warning message:
INFO: rcu_bh_state detected stalls on CPUs/tasks: { } (detected by 4, 2502 jiffies)
This is rare, but does happen from time to time in real life.
So your kernel printed an RCU CPU stall warning. The next question is
"What caused it?" The following problems can result in RCU CPU stall
warnings:
o A CPU looping in an RCU read-side critical section.
o A CPU looping with interrupts disabled.
o A CPU looping with interrupts disabled. This condition can
result in RCU-sched and RCU-bh stalls.
o A CPU looping with preemption disabled.
o A CPU looping with preemption disabled. This condition can
result in RCU-sched stalls and, if ksoftirqd is in use, RCU-bh
stalls.
o A CPU looping with bottom halves disabled. This condition can
result in RCU-sched and RCU-bh stalls.
o For !CONFIG_PREEMPT kernels, a CPU looping anywhere in the kernel
without invoking schedule().
@ -39,20 +83,24 @@ o For !CONFIG_PREEMPT kernels, a CPU looping anywhere in the kernel
o A bug in the RCU implementation.
o A hardware failure. This is quite unlikely, but has occurred
at least once in a former life. A CPU failed in a running system,
at least once in real life. A CPU failed in a running system,
becoming unresponsive, but not causing an immediate crash.
This resulted in a series of RCU CPU stall warnings, eventually
leading the realization that the CPU had failed.
The RCU, RCU-sched, and RCU-bh implementations have CPU stall warning.
SRCU does not do so directly, but its calls to synchronize_sched() will
result in RCU-sched detecting any CPU stalls that might be occurring.
The RCU, RCU-sched, and RCU-bh implementations have CPU stall
warning. SRCU does not have its own CPU stall warnings, but its
calls to synchronize_sched() will result in RCU-sched detecting
RCU-sched-related CPU stalls. Please note that RCU only detects
CPU stalls when there is a grace period in progress. No grace period,
no CPU stall warnings.
To diagnose the cause of the stall, inspect the stack traces. The offending
function will usually be near the top of the stack. If you have a series
of stall warnings from a single extended stall, comparing the stack traces
can often help determine where the stall is occurring, which will usually
be in the function nearest the top of the stack that stays the same from
trace to trace.
To diagnose the cause of the stall, inspect the stack traces.
The offending function will usually be near the top of the stack.
If you have a series of stall warnings from a single extended stall,
comparing the stack traces can often help determine where the stall
is occurring, which will usually be in the function nearest the top of
that portion of the stack which remains the same from trace to trace.
If you can reliably trigger the stall, ftrace can be quite helpful.
RCU bugs can often be debugged with the help of CONFIG_RCU_TRACE.

10
Documentation/RCU/torture.txt
View File

@ -182,16 +182,6 @@ Similarly, sched_expedited RCU provides the following:
sched_expedited-torture: Reader Pipe: 12660320201 95875 0 0 0 0 0 0 0 0 0
sched_expedited-torture: Reader Batch: 12660424885 0 0 0 0 0 0 0 0 0 0
sched_expedited-torture: Free-Block Circulation: 1090795 1090795 1090794 1090793 1090792 1090791 1090790 1090789 1090788 1090787 0
state: -1 / 0:0 3:0 4:0
As before, the first four lines are similar to those for RCU.
The last line shows the task-migration state. The first number is
-1 if synchronize_sched_expedited() is idle, -2 if in the process of
posting wakeups to the migration kthreads, and N when waiting on CPU N.
Each of the colon-separated fields following the "/" is a CPU:state pair.
Valid states are "0" for idle, "1" for waiting for quiescent state,
"2" for passed through quiescent state, and "3" when a race with a
CPU-hotplug event forces use of the synchronize_sched() primitive.
USAGE

35
Documentation/RCU/trace.txt
View File

@ -256,23 +256,23 @@ o Each element of the form "1/1 0:127 ^0" represents one struct
The output of "cat rcu/rcu_pending" looks as follows:
rcu_sched:
0 np=255892 qsp=53936 cbr=0 cng=14417 gpc=10033 gps=24320 nf=6445 nn=146741
1 np=261224 qsp=54638 cbr=0 cng=25723 gpc=16310 gps=2849 nf=5912 nn=155792
2 np=237496 qsp=49664 cbr=0 cng=2762 gpc=45478 gps=1762 nf=1201 nn=136629
3 np=236249 qsp=48766 cbr=0 cng=286 gpc=48049 gps=1218 nf=207 nn=137723
4 np=221310 qsp=46850 cbr=0 cng=26 gpc=43161 gps=4634 nf=3529 nn=123110
5 np=237332 qsp=48449 cbr=0 cng=54 gpc=47920 gps=3252 nf=201 nn=137456
6 np=219995 qsp=46718 cbr=0 cng=50 gpc=42098 gps=6093 nf=4202 nn=120834
7 np=249893 qsp=49390 cbr=0 cng=72 gpc=38400 gps=17102 nf=41 nn=144888
0 np=255892 qsp=53936 rpq=85 cbr=0 cng=14417 gpc=10033 gps=24320 nf=6445 nn=146741
1 np=261224 qsp=54638 rpq=33 cbr=0 cng=25723 gpc=16310 gps=2849 nf=5912 nn=155792
2 np=237496 qsp=49664 rpq=23 cbr=0 cng=2762 gpc=45478 gps=1762 nf=1201 nn=136629
3 np=236249 qsp=48766 rpq=98 cbr=0 cng=286 gpc=48049 gps=1218 nf=207 nn=137723
4 np=221310 qsp=46850 rpq=7 cbr=0 cng=26 gpc=43161 gps=4634 nf=3529 nn=123110
5 np=237332 qsp=48449 rpq=9 cbr=0 cng=54 gpc=47920 gps=3252 nf=201 nn=137456
6 np=219995 qsp=46718 rpq=12 cbr=0 cng=50 gpc=42098 gps=6093 nf=4202 nn=120834
7 np=249893 qsp=49390 rpq=42 cbr=0 cng=72 gpc=38400 gps=17102 nf=41 nn=144888
rcu_bh:
0 np=146741 qsp=1419 cbr=0 cng=6 gpc=0 gps=0 nf=2 nn=145314
1 np=155792 qsp=12597 cbr=0 cng=0 gpc=4 gps=8 nf=3 nn=143180
2 np=136629 qsp=18680 cbr=0 cng=0 gpc=7 gps=6 nf=0 nn=117936
3 np=137723 qsp=2843 cbr=0 cng=0 gpc=10 gps=7 nf=0 nn=134863
4 np=123110 qsp=12433 cbr=0 cng=0 gpc=4 gps=2 nf=0 nn=110671
5 np=137456 qsp=4210 cbr=0 cng=0 gpc=6 gps=5 nf=0 nn=133235
6 np=120834 qsp=9902 cbr=0 cng=0 gpc=6 gps=3 nf=2 nn=110921
7 np=144888 qsp=26336 cbr=0 cng=0 gpc=8 gps=2 nf=0 nn=118542
0 np=146741 qsp=1419 rpq=6 cbr=0 cng=6 gpc=0 gps=0 nf=2 nn=145314
1 np=155792 qsp=12597 rpq=3 cbr=0 cng=0 gpc=4 gps=8 nf=3 nn=143180
2 np=136629 qsp=18680 rpq=1 cbr=0 cng=0 gpc=7 gps=6 nf=0 nn=117936
3 np=137723 qsp=2843 rpq=0 cbr=0 cng=0 gpc=10 gps=7 nf=0 nn=134863
4 np=123110 qsp=12433 rpq=0 cbr=0 cng=0 gpc=4 gps=2 nf=0 nn=110671
5 np=137456 qsp=4210 rpq=1 cbr=0 cng=0 gpc=6 gps=5 nf=0 nn=133235
6 np=120834 qsp=9902 rpq=2 cbr=0 cng=0 gpc=6 gps=3 nf=2 nn=110921
7 np=144888 qsp=26336 rpq=0 cbr=0 cng=0 gpc=8 gps=2 nf=0 nn=118542
As always, this is once again split into "rcu_sched" and "rcu_bh"
portions, with CONFIG_TREE_PREEMPT_RCU kernels having an additional
@ -284,6 +284,9 @@ o "np" is the number of times that __rcu_pending() has been invoked
o "qsp" is the number of times that the RCU was waiting for a
quiescent state from this CPU.
o "rpq" is the number of times that the CPU had passed through
a quiescent state, but not yet reported it to RCU.
o "cbr" is the number of times that this CPU had RCU callbacks
that had passed through a grace period, and were thus ready
to be invoked.

2
Documentation/Smack.txt
View File

@ -73,7 +73,7 @@ NOTE: Smack labels are limited to 23 characters. The attr command
If you don't do anything special all users will get the floor ("_")
label when they log in. If you do want to log in via the hacked ssh
at other labels use the attr command to set the smack value on the
home directory and it's contents.
home directory and its contents.
You can add access rules in /etc/smack/accesses. They take the form:

2
Documentation/arm/00-INDEX
View File

@ -20,6 +20,8 @@ Samsung-S3C24XX
- S3C24XX ARM Linux Overview
Sharp-LH
- Linux on Sharp LH79524 and LH7A40X System On a Chip (SOC)
SPEAr
- ST SPEAr platform Linux Overview
VFP/
- Release notes for Linux Kernel Vector Floating Point support code
empeg/

2
Documentation/arm/SA1100/ADSBitsy
View File

@ -32,7 +32,7 @@ Notes:
- The flash on board is divided into 3 partitions.
You should be careful to use flash on board.
It's partition is different from GraphicsClient Plus and GraphicsMaster
Its partition is different from GraphicsClient Plus and GraphicsMaster
- 16bpp mode requires a different cable than what ships with the board.
Contact ADS or look through the manual to wire your own. Currently,

60
Documentation/arm/SPEAr/overview.txt Normal file
View File

@ -0,0 +1,60 @@
SPEAr ARM Linux Overview
==========================
Introduction
------------
SPEAr (Structured Processor Enhanced Architecture).
weblink : http://www.st.com/spear
The ST Microelectronics SPEAr range of ARM9/CortexA9 System-on-Chip CPUs are
supported by the 'spear' platform of ARM Linux. Currently SPEAr300,
SPEAr310, SPEAr320 and SPEAr600 SOCs are supported. Support for the SPEAr13XX
series is in progress.
Hierarchy in SPEAr is as follows:
SPEAr (Platform)
- SPEAr3XX (3XX SOC series, based on ARM9)
- SPEAr300 (SOC)
- SPEAr300_EVB (Evaluation Board)
- SPEAr310 (SOC)
- SPEAr310_EVB (Evaluation Board)
- SPEAr320 (SOC)
- SPEAr320_EVB (Evaluation Board)
- SPEAr6XX (6XX SOC series, based on ARM9)
- SPEAr600 (SOC)
- SPEAr600_EVB (Evaluation Board)
- SPEAr13XX (13XX SOC series, based on ARM CORTEXA9)
- SPEAr1300 (SOC)
Configuration
-------------
A generic configuration is provided for each machine, and can be used as the
default by
make spear600_defconfig
make spear300_defconfig
make spear310_defconfig
make spear320_defconfig
Layout
------
The common files for multiple machine families (SPEAr3XX, SPEAr6XX and
SPEAr13XX) are located in the platform code contained in arch/arm/plat-spear
with headers in plat/.
Each machine series have a directory with name arch/arm/mach-spear followed by
series name. Like mach-spear3xx, mach-spear6xx and mach-spear13xx.
Common file for machines of spear3xx family is mach-spear3xx/spear3xx.c and for
spear6xx is mach-spear6xx/spear6xx.c. mach-spear* also contain soc/machine
specific files, like spear300.c, spear310.c, spear320.c and spear600.c.
mach-spear* also contains board specific files for each machine type.
Document Author
---------------
Viresh Kumar, (c) 2010 ST Microelectronics

2
Documentation/arm/Sharp-LH/ADC-LH7-Touchscreen
View File

@ -7,7 +7,7 @@ The driver only implements a four-wire touch panel protocol.
The touchscreen driver is maintenance free except for the pen-down or
touch threshold. Some resistive displays and board combinations may
require tuning of this threshold. The driver exposes some of it's
require tuning of this threshold. The driver exposes some of its
internal state in the sys filesystem. If the kernel is configured
with it, CONFIG_SYSFS, and sysfs is mounted at /sys, there will be a
directory

2
Documentation/atomic_ops.txt
View File

@ -320,7 +320,7 @@ counter decrement would not become globally visible until the
obj->active update does.
As a historical note, 32-bit Sparc used to only allow usage of
24-bits of it's atomic_t type. This was because it used 8 bits
24-bits of its atomic_t type. This was because it used 8 bits
as a spinlock for SMP safety. Sparc32 lacked a "compare and swap"
type instruction. However, 32-bit Sparc has since been moved over
to a "hash table of spinlocks" scheme, that allows the full 32-bit

2
Documentation/blackfin/bfin-gpio-notes.txt
View File

@ -43,7 +43,7 @@
void bfin_gpio_irq_free(unsigned gpio);
The request functions will record the function state for a certain pin,
the free functions will clear it's function state.
the free functions will clear its function state.
Once a pin is requested, it can't be requested again before it is freed by
previous caller, otherwise kernel will dump stacks, and the request
function fail.

6
Documentation/cachetlb.txt
View File

@ -5,7 +5,7 @@
This document describes the cache/tlb flushing interfaces called
by the Linux VM subsystem. It enumerates over each interface,
describes it's intended purpose, and what side effect is expected
describes its intended purpose, and what side effect is expected
after the interface is invoked.
The side effects described below are stated for a uniprocessor
@ -231,7 +231,7 @@ require a whole different set of interfaces to handle properly.
The biggest problem is that of virtual aliasing in the data cache
of a processor.
Is your port susceptible to virtual aliasing in it's D-cache?
Is your port susceptible to virtual aliasing in its D-cache?
Well, if your D-cache is virtually indexed, is larger in size than
PAGE_SIZE, and does not prevent multiple cache lines for the same
physical address from existing at once, you have this problem.
@ -249,7 +249,7 @@ one way to solve this (in particular SPARC_FLAG_MMAPSHARED).
Next, you have to solve the D-cache aliasing issue for all
other cases. Please keep in mind that fact that, for a given page
mapped into some user address space, there is always at least one more
mapping, that of the kernel in it's linear mapping starting at
mapping, that of the kernel in its linear mapping starting at
PAGE_OFFSET. So immediately, once the first user maps a given
physical page into its address space, by implication the D-cache
aliasing problem has the potential to exist since the kernel already

2
Documentation/cgroups/cgroups.txt
View File

@ -572,7 +572,7 @@ void cancel_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
Called when a task attach operation has failed after can_attach() has succeeded.
A subsystem whose can_attach() has some side-effects should provide this
function, so that the subsytem can implement a rollback. If not, not necessary.
function, so that the subsystem can implement a rollback. If not, not necessary.
This will be called only about subsystems whose can_attach() operation have
succeeded.

38
Documentation/cgroups/cpusets.txt
View File

@ -42,7 +42,7 @@ Nodes to a set of tasks. In this document "Memory Node" refers to
an on-line node that contains memory.
Cpusets constrain the CPU and Memory placement of tasks to only
the resources within a tasks current cpuset. They form a nested
the resources within a task's current cpuset. They form a nested
hierarchy visible in a virtual file system. These are the essential
hooks, beyond what is already present, required to manage dynamic
job placement on large systems.
@ -53,11 +53,11 @@ Documentation/cgroups/cgroups.txt.
Requests by a task, using the sched_setaffinity(2) system call to
include CPUs in its CPU affinity mask, and using the mbind(2) and
set_mempolicy(2) system calls to include Memory Nodes in its memory
policy, are both filtered through that tasks cpuset, filtering out any
policy, are both filtered through that task's cpuset, filtering out any
CPUs or Memory Nodes not in that cpuset. The scheduler will not
schedule a task on a CPU that is not allowed in its cpus_allowed
vector, and the kernel page allocator will not allocate a page on a
node that is not allowed in the requesting tasks mems_allowed vector.
node that is not allowed in the requesting task's mems_allowed vector.
User level code may create and destroy cpusets by name in the cgroup
virtual file system, manage the attributes and permissions of these
@ -121,9 +121,9 @@ Cpusets extends these two mechanisms as follows:
- Each task in the system is attached to a cpuset, via a pointer
in the task structure to a reference counted cgroup structure.
- Calls to sched_setaffinity are filtered to just those CPUs
allowed in that tasks cpuset.
allowed in that task's cpuset.
- Calls to mbind and set_mempolicy are filtered to just
those Memory Nodes allowed in that tasks cpuset.
those Memory Nodes allowed in that task's cpuset.
- The root cpuset contains all the systems CPUs and Memory
Nodes.
- For any cpuset, one can define child cpusets containing a subset
@ -141,11 +141,11 @@ into the rest of the kernel, none in performance critical paths:
- in init/main.c, to initialize the root cpuset at system boot.
- in fork and exit, to attach and detach a task from its cpuset.
- in sched_setaffinity, to mask the requested CPUs by what's
allowed in that tasks cpuset.
allowed in that task's cpuset.
- in sched.c migrate_live_tasks(), to keep migrating tasks within
the CPUs allowed by their cpuset, if possible.
- in the mbind and set_mempolicy system calls, to mask the requested
Memory Nodes by what's allowed in that tasks cpuset.
Memory Nodes by what's allowed in that task's cpuset.
- in page_alloc.c, to restrict memory to allowed nodes.
- in vmscan.c, to restrict page recovery to the current cpuset.
@ -155,7 +155,7 @@ new system calls are added for cpusets - all support for querying and
modifying cpusets is via this cpuset file system.
The /proc/<pid>/status file for each task has four added lines,
displaying the tasks cpus_allowed (on which CPUs it may be scheduled)
displaying the task's cpus_allowed (on which CPUs it may be scheduled)
and mems_allowed (on which Memory Nodes it may obtain memory),
in the two formats seen in the following example:
@ -323,17 +323,17 @@ stack segment pages of a task.
By default, both kinds of memory spreading are off, and memory
pages are allocated on the node local to where the task is running,
except perhaps as modified by the tasks NUMA mempolicy or cpuset
except perhaps as modified by the task's NUMA mempolicy or cpuset
configuration, so long as sufficient free memory pages are available.
When new cpusets are created, they inherit the memory spread settings
of their parent.
Setting memory spreading causes allocations for the affected page
or slab caches to ignore the tasks NUMA mempolicy and be spread
or slab caches to ignore the task's NUMA mempolicy and be spread
instead. Tasks using mbind() or set_mempolicy() calls to set NUMA
mempolicies will not notice any change in these calls as a result of
their containing tasks memory spread settings. If memory spreading
their containing task's memory spread settings. If memory spreading
is turned off, then the currently specified NUMA mempolicy once again
applies to memory page allocations.
@ -357,7 +357,7 @@ pages from the node returned by cpuset_mem_spread_node().
The cpuset_mem_spread_node() routine is also simple. It uses the
value of a per-task rotor cpuset_mem_spread_rotor to select the next
node in the current tasks mems_allowed to prefer for the allocation.
node in the current task's mems_allowed to prefer for the allocation.
This memory placement policy is also known (in other contexts) as
round-robin or interleave.
@ -594,7 +594,7 @@ is attached, is subtle.
If a cpuset has its Memory Nodes modified, then for each task attached
to that cpuset, the next time that the kernel attempts to allocate
a page of memory for that task, the kernel will notice the change
in the tasks cpuset, and update its per-task memory placement to
in the task's cpuset, and update its per-task memory placement to
remain within the new cpusets memory placement. If the task was using
mempolicy MPOL_BIND, and the nodes to which it was bound overlap with
its new cpuset, then the task will continue to use whatever subset
@ -603,13 +603,13 @@ was using MPOL_BIND and now none of its MPOL_BIND nodes are allowed
in the new cpuset, then the task will be essentially treated as if it
was MPOL_BIND bound to the new cpuset (even though its NUMA placement,
as queried by get_mempolicy(), doesn't change). If a task is moved
from one cpuset to another, then the kernel will adjust the tasks
from one cpuset to another, then the kernel will adjust the task's
memory placement, as above, the next time that the kernel attempts
to allocate a page of memory for that task.
If a cpuset has its 'cpuset.cpus' modified, then each task in that cpuset
will have its allowed CPU placement changed immediately. Similarly,
if a tasks pid is written to another cpusets 'cpuset.tasks' file, then its
if a task's pid is written to another cpusets 'cpuset.tasks' file, then its
allowed CPU placement is changed immediately. If such a task had been
bound to some subset of its cpuset using the sched_setaffinity() call,
the task will be allowed to run on any CPU allowed in its new cpuset,
@ -626,16 +626,16 @@ cpusets memory placement policy 'cpuset.mems' subsequently changes.
If the cpuset flag file 'cpuset.memory_migrate' is set true, then when
tasks are attached to that cpuset, any pages that task had
allocated to it on nodes in its previous cpuset are migrated
to the tasks new cpuset. The relative placement of the page within
to the task's new cpuset. The relative placement of the page within
the cpuset is preserved during these migration operations if possible.
For example if the page was on the second valid node of the prior cpuset
then the page will be placed on the second valid node of the new cpuset.
Also if 'cpuset.memory_migrate' is set true, then if that cpusets
Also if 'cpuset.memory_migrate' is set true, then if that cpuset's
'cpuset.mems' file is modified, pages allocated to tasks in that
cpuset, that were on nodes in the previous setting of 'cpuset.mems',
will be moved to nodes in the new setting of 'mems.'
Pages that were not in the tasks prior cpuset, or in the cpusets
Pages that were not in the task's prior cpuset, or in the cpuset's
prior 'cpuset.mems' setting, will not be moved.
There is an exception to the above. If hotplug functionality is used
@ -655,7 +655,7 @@ There is a second exception to the above. GFP_ATOMIC requests are
kernel internal allocations that must be satisfied, immediately.
The kernel may drop some request, in rare cases even panic, if a
GFP_ATOMIC alloc fails. If the request cannot be satisfied within
the current tasks cpuset, then we relax the cpuset, and look for
the current task's cpuset, then we relax the cpuset, and look for
memory anywhere we can find it. It's better to violate the cpuset
than stress the kernel.

2
Documentation/cgroups/memcg_test.txt
View File

@ -244,7 +244,7 @@ Under below explanation, we assume CONFIG_MEM_RES_CTRL_SWAP=y.
we have to check if OLDPAGE/NEWPAGE is a valid page after commit().
8. LRU
Each memcg has its own private LRU. Now, it's handling is under global
Each memcg has its own private LRU. Now, its handling is under global
VM's control (means that it's handled under global zone->lru_lock).
Almost all routines around memcg's LRU is called by global LRU's
list management functions under zone->lru_lock().

2
Documentation/cgroups/memory.txt
View File

@ -263,7 +263,7 @@ some of the pages cached in the cgroup (page cache pages).
4.2 Task migration
When a task migrates from one cgroup to another, it's charge is not
When a task migrates from one cgroup to another, its charge is not
carried forward by default. The pages allocated from the original cgroup still
remain charged to it, the charge is dropped when the page is freed or
reclaimed.

2
Documentation/connector/connector.txt
View File

@ -88,7 +88,7 @@ int cn_netlink_send(struct cn_msg *msg, u32 __groups, int gfp_mask);
int gfp_mask - GFP mask.
Note: When registering new callback user, connector core assigns
netlink group to the user which is equal to it's id.idx.
netlink group to the user which is equal to its id.idx.
/*****************************************/
Protocol description.

14
Documentation/credentials.txt
View File

@ -408,9 +408,6 @@ This should be used inside the RCU read lock, as in the following example:
...
}
A function need not get RCU read lock to use __task_cred() if it is holding a
spinlock at the time as this implicitly holds the RCU read lock.
Should it be necessary to hold another task's credentials for a long period of
time, and possibly to sleep whilst doing so, then the caller should get a
reference on them using:
@ -426,17 +423,16 @@ credentials, hiding the RCU magic from the caller:
uid_t task_uid(task) Task's real UID
uid_t task_euid(task) Task's effective UID
If the caller is holding a spinlock or the RCU read lock at the time anyway,
then:
If the caller is holding the RCU read lock at the time anyway, then:
__task_cred(task)->uid
__task_cred(task)->euid
should be used instead. Similarly, if multiple aspects of a task's credentials
need to be accessed, RCU read lock or a spinlock should be used, __task_cred()
called, the result stored in a temporary pointer and then the credential
aspects called from that before dropping the lock. This prevents the
potentially expensive RCU magic from being invoked multiple times.
need to be accessed, RCU read lock should be used, __task_cred() called, the
result stored in a temporary pointer and then the credential aspects called
from that before dropping the lock. This prevents the potentially expensive
RCU magic from being invoked multiple times.
Should some other single aspect of another task's credentials need to be
accessed, then this can be used:

2
Documentation/dvb/ci.txt
View File

@ -41,7 +41,7 @@ This application requires the following to function properly as of now.
* Cards that fall in this category
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
At present the cards that fall in this category are the Twinhan and it's
At present the cards that fall in this category are the Twinhan and its
clones, these cards are available as VVMER, Tomato, Hercules, Orange and
so on.

2
Documentation/dvb/contributors.txt
View File

@ -1,7 +1,7 @@
Thanks go to the following people for patches and contributions:
Michael Hunold <m.hunold@gmx.de>
for the initial saa7146 driver and it's recent overhaul
for the initial saa7146 driver and its recent overhaul
Christian Theiss
for his work on the initial Linux DVB driver

111
Documentation/feature-removal-schedule.txt
View File

@ -241,16 +241,6 @@ Who: Thomas Gleixner <tglx@linutronix.de>
---------------------------
What (Why):
- xt_recent: the old ipt_recent proc dir
(superseded by /proc/net/xt_recent)
When: January 2009 or Linux 2.7.0, whichever comes first
Why: Superseded by newer revisions or modules
Who: Jan Engelhardt <jengelh@computergmbh.de>
---------------------------
What: GPIO autorequest on gpio_direction_{input,output}() in gpiolib
When: February 2010
Why: All callers should use explicit gpio_request()/gpio_free().
@ -520,26 +510,21 @@ Who: Hans de Goede <hdegoede@redhat.com>
----------------------------
What: corgikbd, spitzkbd, tosakbd driver
When: 2.6.35
Files: drivers/input/keyboard/{corgi,spitz,tosa}kbd.c
Why: We now have a generic GPIO based matrix keyboard driver that
are fully capable of handling all the keys on these devices.
The original drivers manipulate the GPIO registers directly
and so are difficult to maintain.
Who: Eric Miao <eric.y.miao@gmail.com>
What: sysfs-class-rfkill state file
When: Feb 2014
Files: net/rfkill/core.c
Why: Documented as obsolete since Feb 2010. This file is limited to 3
states while the rfkill drivers can have 4 states.
Who: anybody or Florian Mickler <florian@mickler.org>
----------------------------
What: corgi_ssp and corgi_ts driver
When: 2.6.35
Files: arch/arm/mach-pxa/corgi_ssp.c, drivers/input/touchscreen/corgi_ts.c
Why: The corgi touchscreen is now deprecated in favour of the generic
ads7846.c driver. The noise reduction technique used in corgi_ts.c,
that's to wait till vsync before ADC sampling, is also integrated into
ads7846 driver now. Provided that the original driver is not generic
and is difficult to maintain, it will be removed later.
Who: Eric Miao <eric.y.miao@gmail.com>
What: sysfs-class-rfkill claim file
When: Feb 2012
Files: net/rfkill/core.c
Why: It is not possible to claim an rfkill driver since 2007. This is
Documented as obsolete since Feb 2010.
Who: anybody or Florian Mickler <florian@mickler.org>
----------------------------
@ -564,6 +549,16 @@ Who: Avi Kivity <avi@redhat.com>
----------------------------
What: xtime, wall_to_monotonic
When: 2.6.36+
Files: kernel/time/timekeeping.c include/linux/time.h
Why: Cleaning up timekeeping internal values. Please use
existing timekeeping accessor functions to access
the equivalent functionality.
Who: John Stultz <johnstul@us.ibm.com>
----------------------------
What: KVM kernel-allocated memory slots
When: July 2010
Why: Since 2.6.25, kvm supports user-allocated memory slots, which are
@ -589,3 +584,65 @@ Why: Useful in 2003, implementation is a hack.
Generally invoked by accident today.
Seen as doing more harm than good.
Who: Len Brown <len.brown@intel.com>
----------------------------
What: iwlwifi 50XX module parameters
When: 2.6.40
Why: The "..50" modules parameters were used to configure 5000 series and
up devices; different set of module parameters also available for 4965
with same functionalities. Consolidate both set into single place
in drivers/net/wireless/iwlwifi/iwl-agn.c
Who: Wey-Yi Guy <wey-yi.w.guy@intel.com>
----------------------------
What: iwl4965 alias support
When: 2.6.40
Why: Internal alias support has been present in module-init-tools for some
time, the MODULE_ALIAS("iwl4965") boilerplate aliases can be removed
with no impact.
Who: Wey-Yi Guy <wey-yi.w.guy@intel.com>
---------------------------
What: xt_NOTRACK
Files: net/netfilter/xt_NOTRACK.c
When: April 2011
Why: Superseded by xt_CT
Who: Netfilter developer team <netfilter-devel@vger.kernel.org>
---------------------------
What: video4linux /dev/vtx teletext API support
When: 2.6.35
Files: drivers/media/video/saa5246a.c drivers/media/video/saa5249.c
include/linux/videotext.h
Why: The vtx device nodes have been superseded by vbi device nodes
for many years. No applications exist that use the vtx support.
Of the two i2c drivers that actually support this API the saa5249
has been impossible to use for a year now and no known hardware
that supports this device exists. The saa5246a is theoretically
supported by the old mxb boards, but it never actually worked.
In summary: there is no hardware that can use this API and there
are no applications actually implementing this API.
The vtx support still reserves minors 192-223 and we would really
like to reuse those for upcoming new functionality. In the unlikely
event that new hardware appears that wants to use the functionality
provided by the vtx API, then that functionality should be build
around the sliced VBI API instead.
Who: Hans Verkuil <hverkuil@xs4all.nl>
----------------------------
What: IRQF_DISABLED
When: 2.6.36
Why: The flag is a NOOP as we run interrupt handlers with interrupts disabled
Who: Thomas Gleixner <tglx@linutronix.de>
----------------------------

4
Documentation/filesystems/Locking
View File

@ -178,7 +178,7 @@ prototypes:
locking rules:
All except set_page_dirty may block
BKL PageLocked(page) i_sem
BKL PageLocked(page) i_mutex
writepage: no yes, unlocks (see below)
readpage: no yes, unlocks
sync_page: no maybe
@ -429,7 +429,7 @@ check_flags: no
implementations. If your fs is not using generic_file_llseek, you
need to acquire and release the appropriate locks in your ->llseek().
For many filesystems, it is probably safe to acquire the inode
semaphore. Note some filesystems (i.e. remote ones) provide no
mutex. Note some filesystems (i.e. remote ones) provide no
protection for i_size so you will need to use the BKL.
Note: ext2_release() was *the* source of contention on fs-intensive

2
Documentation/filesystems/autofs4-mount-control.txt
View File

@ -146,7 +146,7 @@ found to be inadequate, in this case. The Generic Netlink system was
used for this as raw Netlink would lead to a significant increase in
complexity. There's no question that the Generic Netlink system is an
elegant solution for common case ioctl functions but it's not a complete
replacement probably because it's primary purpose in life is to be a
replacement probably because its primary purpose in life is to be a
message bus implementation rather than specifically an ioctl replacement.
While it would be possible to work around this there is one concern
that lead to the decision to not use it. This is that the autofs

2
Documentation/filesystems/ceph.txt
View File

@ -90,7 +90,7 @@ Mount Options
Specify the IP and/or port the client should bind to locally.
There is normally not much reason to do this. If the IP is not
specified, the client's IP address is determined by looking at the
address it's connection to the monitor originates from.
address its connection to the monitor originates from.
wsize=X
Specify the maximum write size in bytes. By default there is no

2
Documentation/filesystems/dlmfs.txt
View File

@ -47,7 +47,7 @@ You'll want to start heartbeating on a volume which all the nodes in
your lockspace can access. The easiest way to do this is via
ocfs2_hb_ctl (distributed with ocfs2-tools). Right now it requires
that an OCFS2 file system be in place so that it can automatically
find it's heartbeat area, though it will eventually support heartbeat
find its heartbeat area, though it will eventually support heartbeat
against raw disks.
Please see the ocfs2_hb_ctl and mkfs.ocfs2 manual pages distributed

15
Documentation/filesystems/ext3.txt
View File

@ -59,8 +59,19 @@ commit=nrsec (*) Ext3 can be told to sync all its data and metadata
Setting it to very large values will improve
performance.
barrier=1 This enables/disables barriers. barrier=0 disables
it, barrier=1 enables it.
barrier=<0(*)|1> This enables/disables the use of write barriers in
barrier the jbd code. barrier=0 disables, barrier=1 enables.
nobarrier (*) This also requires an IO stack which can support
barriers, and if jbd gets an error on a barrier
write, it will disable again with a warning.
Write barriers enforce proper on-disk ordering
of journal commits, making volatile disk write caches
safe to use, at some performance penalty. If
your disks are battery-backed in one way or another,
disabling barriers may safely improve performance.
The mount options "barrier" and "nobarrier" can
also be used to enable or disable barriers, for
consistency with other ext3 mount options.
orlov (*) This enables the new Orlov block allocator. It is
enabled by default.

12
Documentation/filesystems/fiemap.txt
View File

@ -38,7 +38,7 @@ flags, it will return EBADR and the contents of fm_flags will contain
the set of flags which caused the error. If the kernel is compatible
with all flags passed, the contents of fm_flags will be unmodified.
It is up to userspace to determine whether rejection of a particular
flag is fatal to it's operation. This scheme is intended to allow the
flag is fatal to its operation. This scheme is intended to allow the
fiemap interface to grow in the future but without losing
compatibility with old software.
@ -56,7 +56,7 @@ If this flag is set, the kernel will sync the file before mapping extents.
* FIEMAP_FLAG_XATTR
If this flag is set, the extents returned will describe the inodes
extended attribute lookup tree, instead of it's data tree.
extended attribute lookup tree, instead of its data tree.
Extent Mapping
@ -89,7 +89,7 @@ struct fiemap_extent {
};
All offsets and lengths are in bytes and mirror those on disk. It is valid
for an extents logical offset to start before the request or it's logical
for an extents logical offset to start before the request or its logical
length to extend past the request. Unless FIEMAP_EXTENT_NOT_ALIGNED is
returned, fe_logical, fe_physical, and fe_length will be aligned to the
block size of the file system. With the exception of extents flagged as
@ -125,7 +125,7 @@ been allocated for the file yet.
* FIEMAP_EXTENT_DELALLOC
- This will also set FIEMAP_EXTENT_UNKNOWN.
Delayed allocation - while there is data for this extent, it's
Delayed allocation - while there is data for this extent, its
physical location has not been allocated yet.
* FIEMAP_EXTENT_ENCODED
@ -159,7 +159,7 @@ Data is located within a meta data block.
Data is packed into a block with data from other files.
* FIEMAP_EXTENT_UNWRITTEN
Unwritten extent - the extent is allocated but it's data has not been
Unwritten extent - the extent is allocated but its data has not been
initialized. This indicates the extent's data will be all zero if read
through the filesystem but the contents are undefined if read directly from
the device.
@ -176,7 +176,7 @@ VFS -> File System Implementation
File systems wishing to support fiemap must implement a ->fiemap callback on
their inode_operations structure. The fs ->fiemap call is responsible for
defining it's set of supported fiemap flags, and calling a helper function on
defining its set of supported fiemap flags, and calling a helper function on
each discovered extent:
struct inode_operations {

4
Documentation/filesystems/fuse.txt
View File

@ -91,7 +91,7 @@ Mount options
'default_permissions'
By default FUSE doesn't check file access permissions, the
filesystem is free to implement it's access policy or leave it to
filesystem is free to implement its access policy or leave it to
the underlying file access mechanism (e.g. in case of network
filesystems). This option enables permission checking, restricting
access based on file mode. It is usually useful together with the
@ -171,7 +171,7 @@ or may honor them by sending a reply to the _original_ request, with
the error set to EINTR.
It is also possible that there's a race between processing the
original request and it's INTERRUPT request. There are two possibilities:
original request and its INTERRUPT request. There are two possibilities:
1) The INTERRUPT request is processed before the original request is
processed

12
Documentation/filesystems/gfs2.txt
View File

@ -1,7 +1,7 @@
Global File System
------------------
http://sources.redhat.com/cluster/
http://sources.redhat.com/cluster/wiki/
GFS is a cluster file system. It allows a cluster of computers to
simultaneously use a block device that is shared between them (with FC,
@ -36,11 +36,11 @@ GFS2 is not on-disk compatible with previous versions of GFS, but it
is pretty close.
The following man pages can be found at the URL above:
fsck.gfs2 to repair a filesystem
gfs2_grow to expand a filesystem online
gfs2_jadd to add journals to a filesystem online
gfs2_tool to manipulate, examine and tune a filesystem
fsck.gfs2 to repair a filesystem
gfs2_grow to expand a filesystem online
gfs2_jadd to add journals to a filesystem online
gfs2_tool to manipulate, examine and tune a filesystem
gfs2_quota to examine and change quota values in a filesystem
gfs2_convert to convert a gfs filesystem to gfs2 in-place
mount.gfs2 to help mount(8) mount a filesystem
mkfs.gfs2 to make a filesystem
mkfs.gfs2 to make a filesystem

2
Documentation/filesystems/hpfs.txt
View File

@ -103,7 +103,7 @@ to analyze or change OS2SYS.INI.
Codepages
HPFS can contain several uppercasing tables for several codepages and each
file has a pointer to codepage it's name is in. However OS/2 was created in
file has a pointer to codepage its name is in. However OS/2 was created in
America where people don't care much about codepages and so multiple codepages
support is quite buggy. I have Czech OS/2 working in codepage 852 on my disk.
Once I booted English OS/2 working in cp 850 and I created a file on my 852

8
Documentation/filesystems/logfs.txt
View File

@ -59,7 +59,7 @@ Levels
------
Garbage collection (GC) may fail if all data is written
indiscriminately. One requirement of GC is that data is seperated
indiscriminately. One requirement of GC is that data is separated
roughly according to the distance between the tree root and the data.
Effectively that means all file data is on level 0, indirect blocks
are on levels 1, 2, 3 4 or 5 for 1x, 2x, 3x, 4x or 5x indirect blocks,
@ -67,7 +67,7 @@ respectively. Inode file data is on level 6 for the inodes and 7-11
for indirect blocks.
Each segment contains objects of a single level only. As a result,
each level requires its own seperate segment to be open for writing.
each level requires its own separate segment to be open for writing.
Inode File
----------
@ -106,9 +106,9 @@ Vim
---
By cleverly predicting the life time of data, it is possible to
seperate long-living data from short-living data and thereby reduce
separate long-living data from short-living data and thereby reduce
the GC overhead later. Each type of distinc life expectency (vim) can
have a seperate segment open for writing. Each (level, vim) tupel can
have a separate segment open for writing. Each (level, vim) tupel can
be open just once. If an open segment with unknown vim is encountered
at mount time, it is closed and ignored henceforth.

2
Documentation/filesystems/nfs/nfs41-server.txt
View File

@ -137,7 +137,7 @@ NS*| OPENATTR | OPT | | Section 18.17 |
| READ | REQ | | Section 18.22 |
| READDIR | REQ | | Section 18.23 |
| READLINK | OPT | | Section 18.24 |
NS | RECLAIM_COMPLETE | REQ | | Section 18.51 |
| RECLAIM_COMPLETE | REQ | | Section 18.51 |
| RELEASE_LOCKOWNER | MNI | | N/A |
| REMOVE | REQ | | Section 18.25 |
| RENAME | REQ | | Section 18.26 |

2
Documentation/filesystems/nfs/rpc-cache.txt
View File

@ -185,7 +185,7 @@ failed lookup meant a definite 'no'.
request/response format
-----------------------
While each cache is free to use it's own format for requests
While each cache is free to use its own format for requests
and responses over channel, the following is recommended as
appropriate and support routines are available to help:
Each request or response record should be printable ASCII

4
Documentation/filesystems/nilfs2.txt
View File

@ -50,8 +50,8 @@ NILFS2 supports the following mount options:
(*) == default
nobarrier Disables barriers.
errors=continue(*) Keep going on a filesystem error.
errors=remount-ro Remount the filesystem read-only on an error.
errors=continue Keep going on a filesystem error.
errors=remount-ro(*) Remount the filesystem read-only on an error.
errors=panic Panic and halt the machine if an error occurs.
cp=n Specify the checkpoint-number of the snapshot to be
mounted. Checkpoints and snapshots are listed by lscp

7
Documentation/filesystems/ocfs2.txt
View File

@ -80,3 +80,10 @@ user_xattr (*) Enables Extended User Attributes.
nouser_xattr Disables Extended User Attributes.
acl Enables POSIX Access Control Lists support.
noacl (*) Disables POSIX Access Control Lists support.
resv_level=2 (*) Set how agressive allocation reservations will be.
Valid values are between 0 (reservations off) to 8
(maximum space for reservations).
dir_resv_level= (*) By default, directory reservations will scale with file
reservations - users should rarely need to change this
value. If allocation reservations are turned off, this
option will have no effect.

13
Documentation/filesystems/proc.txt
View File

@ -305,7 +305,7 @@ Table 1-4: Contents of the stat files (as of 2.6.30-rc7)
cgtime guest time of the task children in jiffies
..............................................................................
The /proc/PID/map file containing the currently mapped memory regions and
The /proc/PID/maps file containing the currently mapped memory regions and
their access permissions.
The format is:
@ -316,7 +316,7 @@ address perms offset dev inode pathname
08049000-0804a000 rw-p 00001000 03:00 8312 /opt/test
0804a000-0806b000 rw-p 00000000 00:00 0 [heap]
a7cb1000-a7cb2000 ---p 00000000 00:00 0
a7cb2000-a7eb2000 rw-p 00000000 00:00 0 [threadstack:001ff4b4]
a7cb2000-a7eb2000 rw-p 00000000 00:00 0
a7eb2000-a7eb3000 ---p 00000000 00:00 0
a7eb3000-a7ed5000 rw-p 00000000 00:00 0
a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6
@ -352,7 +352,6 @@ is not associated with a file:
[stack] = the stack of the main process
[vdso] = the "virtual dynamic shared object",
the kernel system call handler
[threadstack:xxxxxxxx] = the stack of the thread, xxxxxxxx is the stack size
or if empty, the mapping is anonymous.
@ -566,6 +565,10 @@ The default_smp_affinity mask applies to all non-active IRQs, which are the
IRQs which have not yet been allocated/activated, and hence which lack a
/proc/irq/[0-9]* directory.
The node file on an SMP system shows the node to which the device using the IRQ
reports itself as being attached. This hardware locality information does not
include information about any possible driver locality preference.
prof_cpu_mask specifies which CPUs are to be profiled by the system wide
profiler. Default value is ffffffff (all cpus).
@ -965,7 +968,7 @@ your system and how much traffic was routed over those devices:
...] 1375103 17405 0 0 0 0 0 0
...] 1703981 5535 0 0 0 3 0 0
In addition, each Channel Bond interface has it's own directory. For
In addition, each Channel Bond interface has its own directory. For
example, the bond0 device will have a directory called /proc/net/bond0/.
It will contain information that is specific to that bond, such as the
current slaves of the bond, the link status of the slaves, and how
@ -1362,7 +1365,7 @@ been accounted as having caused 1MB of write.
In other words: The number of bytes which this process caused to not happen,
by truncating pagecache. A task can cause "negative" IO too. If this task
truncates some dirty pagecache, some IO which another task has been accounted
for (in it's write_bytes) will not be happening. We _could_ just subtract that
for (in its write_bytes) will not be happening. We _could_ just subtract that
from the truncating task's write_bytes, but there is information loss in doing
that.

2
Documentation/filesystems/smbfs.txt
View File

@ -3,6 +3,6 @@ protocol used by Windows for Workgroups, Windows 95 and Windows NT.
Smbfs was inspired by Samba, the program written by Andrew Tridgell
that turns any Unix host into a file server for DOS or Windows clients.
Smbfs is a SMB client, but uses parts of samba for it's operation. For
Smbfs is a SMB client, but uses parts of samba for its operation. For
more info on samba, including documentation, please go to
http://www.samba.org/ and then on to your nearest mirror.

42
Documentation/filesystems/sysfs-tagging.txt Normal file
View File

@ -0,0 +1,42 @@
Sysfs tagging
-------------
(Taken almost verbatim from Eric Biederman's netns tagging patch
commit msg)
The problem. Network devices show up in sysfs and with the network
namespace active multiple devices with the same name can show up in
the same directory, ouch!
To avoid that problem and allow existing applications in network
namespaces to see the same interface that is currently presented in
sysfs, sysfs now has tagging directory support.
By using the network namespace pointers as tags to separate out the
the sysfs directory entries we ensure that we don't have conflicts
in the directories and applications only see a limited set of
the network devices.
Each sysfs directory entry may be tagged with zero or one
namespaces. A sysfs_dirent is augmented with a void *s_ns. If a
directory entry is tagged, then sysfs_dirent->s_flags will have a
flag between KOBJ_NS_TYPE_NONE and KOBJ_NS_TYPES, and s_ns will
point to the namespace to which it belongs.
Each sysfs superblock's sysfs_super_info contains an array void
*ns[KOBJ_NS_TYPES]. When a a task in a tagging namespace
kobj_nstype first mounts sysfs, a new superblock is created. It
will be differentiated from other sysfs mounts by having its
s_fs_info->ns[kobj_nstype] set to the new namespace. Note that
through bind mounting and mounts propagation, a task can easily view
the contents of other namespaces' sysfs mounts. Therefore, when a
namespace exits, it will call kobj_ns_exit() to invalidate any
sysfs_dirent->s_ns pointers pointing to it.
Users of this interface:
- define a type in the kobj_ns_type enumeration.
- call kobj_ns_type_register() with its kobj_ns_type_operations which has
- current_ns() which returns current's namespace
- netlink_ns() which returns a socket's namespace
- initial_ns() which returns the initial namesapce
- call kobj_ns_exit() when an individual tag is no longer valid

2
Documentation/filesystems/vfs.txt
View File

@ -72,7 +72,7 @@ structure (this is the kernel-side implementation of file
descriptors). The freshly allocated file structure is initialized with
a pointer to the dentry and a set of file operation member functions.
These are taken from the inode data. The open() file method is then
called so the specific filesystem implementation can do it's work. You
called so the specific filesystem implementation can do its work. You
can see that this is another switch performed by the VFS. The file
structure is placed into the file descriptor table for the process.

2
Documentation/hwmon/lm85
View File

@ -157,7 +157,7 @@ temperature configuration points:
There are three PWM outputs. The LM85 datasheet suggests that the
pwm3 output control both fan3 and fan4. Each PWM can be individually
configured and assigned to a zone for it's control value. Each PWM can be
configured and assigned to a zone for its control value. Each PWM can be
configured individually according to the following options.
* pwm#_auto_pwm_min - this specifies the PWM value for temp#_auto_temp_off

8
Documentation/i2c/busses/i2c-i801
View File

@ -27,7 +27,13 @@ Authors:
Module Parameters
-----------------
None.
* disable_features (bit vector)
Disable selected features normally supported by the device. This makes it
possible to work around possible driver or hardware bugs if the feature in
question doesn't work as intended for whatever reason. Bit values:
1 disable SMBus PEC
2 disable the block buffer
8 disable the I2C block read functionality
Description

5
Documentation/i2c/writing-clients
View File

@ -74,6 +74,11 @@ structure at all. You should use this to keep device-specific data.
/* retrieve the value */
void *i2c_get_clientdata(const struct i2c_client *client);
Note that starting with kernel 2.6.34, you don't have to set the `data' field
to NULL in remove() or if probe() failed anymore. The i2c-core does this
automatically on these occasions. Those are also the only times the core will
touch this field.
Accessing the client
====================

8
Documentation/input/elantech.txt
View File

@ -333,14 +333,14 @@ byte 0:
byte 1:
bit 7 6 5 4 3 2 1 0
x15 x14 x13 x12 x11 x10 x9 x8
. . . . . x10 x9 x8
byte 2:
bit 7 6 5 4 3 2 1 0
x7 x6 x5 x4 x4 x2 x1 x0
x15..x0 = absolute x value (horizontal)
x10..x0 = absolute x value (horizontal)
byte 3:
@ -350,14 +350,14 @@ byte 3:
byte 4:
bit 7 6 5 4 3 2 1 0
y15 y14 y13 y12 y11 y10 y8 y8
. . . . . . y9 y8
byte 5:
bit 7 6 5 4 3 2 1 0
y7 y6 y5 y4 y3 y2 y1 y0
y15..y0 = absolute y value (vertical)
y9..y0 = absolute y value (vertical)
4.2.2 Two finger touch

2
Documentation/input/joystick.txt
View File

@ -402,7 +402,7 @@ for the port of the SoundFusion is supported by the cs461x.c module.
~~~~~~~~~~~~~~~~~~~~~~~~
The Live! has a special PCI gameport, which, although it doesn't provide
any "Enhanced" stuff like 4DWave and friends, is quite a bit faster than
it's ISA counterparts. It also requires special support, hence the
its ISA counterparts. It also requires special support, hence the
emu10k1-gp.c module for it instead of the normal ns558.c one.
3.15 SoundBlaster 64 and 128 - ES1370 and ES1371, ESS Solo1 and S3 SonicVibes

18
Documentation/intel_txt.txt
View File

@ -126,7 +126,7 @@ o Tboot then applies an (optional) user-defined launch policy to
o Tboot adjusts the e820 table provided by the bootloader to reserve
its own location in memory as well as to reserve certain other
TXT-related regions.
o As part of it's launch, tboot DMA protects all of RAM (using the
o As part of its launch, tboot DMA protects all of RAM (using the
VT-d PMRs). Thus, the kernel must be booted with 'intel_iommu=on'
in order to remove this blanket protection and use VT-d's
page-level protection.
@ -161,13 +161,15 @@ o In order to put a system into any of the sleep states after a TXT
has been restored, it will restore the TPM PCRs and then
transfer control back to the kernel's S3 resume vector.
In order to preserve system integrity across S3, the kernel
provides tboot with a set of memory ranges (kernel
code/data/bss, S3 resume code, and AP trampoline) that tboot
will calculate a MAC (message authentication code) over and then
seal with the TPM. On resume and once the measured environment
has been re-established, tboot will re-calculate the MAC and
verify it against the sealed value. Tboot's policy determines
what happens if the verification fails.
provides tboot with a set of memory ranges (RAM and RESERVED_KERN
in the e820 table, but not any memory that BIOS might alter over
the S3 transition) that tboot will calculate a MAC (message
authentication code) over and then seal with the TPM. On resume
and once the measured environment has been re-established, tboot
will re-calculate the MAC and verify it against the sealed value.
Tboot's policy determines what happens if the verification fails.
Note that the c/s 194 of tboot which has the new MAC code supports
this.
That's pretty much it for TXT support.

2
Documentation/kbuild/kconfig-language.txt
View File

@ -181,7 +181,7 @@ Expressions are listed in decreasing order of precedence.
(7) Returns the result of max(/expr/, /expr/).
An expression can have a value of 'n', 'm' or 'y' (or 0, 1, 2
respectively for calculations). A menu entry becomes visible when it's
respectively for calculations). A menu entry becomes visible when its
expression evaluates to 'm' or 'y'.
There are two types of symbols: constant and non-constant symbols.

2
Documentation/kbuild/kconfig.txt
View File

@ -96,7 +96,7 @@ Environment variables for 'silentoldconfig'
KCONFIG_NOSILENTUPDATE
--------------------------------------------------
If this variable has a non-blank value, it prevents silent kernel
config udpates (requires explicit updates).
config updates (requires explicit updates).
KCONFIG_AUTOCONFIG
--------------------------------------------------

10
Documentation/kernel-docs.txt
View File

@ -116,7 +116,7 @@
Author: Ingo Molnar, Gadi Oxman and Miguel de Icaza.
URL: http://www.linuxjournal.com/article.php?sid=2391
Keywords: RAID, MD driver.
Description: Linux Journal Kernel Korner article. Here is it's
Description: Linux Journal Kernel Korner article. Here is its
abstract: "A description of the implementation of the RAID-1,
RAID-4 and RAID-5 personalities of the MD device driver in the
Linux kernel, providing users with high performance and reliable,
@ -127,7 +127,7 @@
URL: http://www.linuxjournal.com/article.php?sid=1219
Keywords: device driver, module, loading/unloading modules,
allocating resources.
Description: Linux Journal Kernel Korner article. Here is it's
Description: Linux Journal Kernel Korner article. Here is its
abstract: "This is the first of a series of four articles
co-authored by Alessandro Rubini and Georg Zezchwitz which present
a practical approach to writing Linux device drivers as kernel
@ -141,7 +141,7 @@
Keywords: character driver, init_module, clean_up module,
autodetection, mayor number, minor number, file operations,
open(), close().
Description: Linux Journal Kernel Korner article. Here is it's
Description: Linux Journal Kernel Korner article. Here is its
abstract: "This article, the second of four, introduces part of
the actual code to create custom module implementing a character
device driver. It describes the code for module initialization and
@ -152,7 +152,7 @@
URL: http://www.linuxjournal.com/article.php?sid=1221
Keywords: read(), write(), select(), ioctl(), blocking/non
blocking mode, interrupt handler.
Description: Linux Journal Kernel Korner article. Here is it's
Description: Linux Journal Kernel Korner article. Here is its
abstract: "This article, the third of four on writing character
device drivers, introduces concepts of reading, writing, and using
ioctl-calls".
@ -161,7 +161,7 @@
Author: Alessandro Rubini and Georg v. Zezschwitz.
URL: http://www.linuxjournal.com/article.php?sid=1222
Keywords: interrupts, irqs, DMA, bottom halves, task queues.
Description: Linux Journal Kernel Korner article. Here is it's
Description: Linux Journal Kernel Korner article. Here is its
abstract: "This is the fourth in a series of articles about
writing character device drivers as loadable kernel modules. This
month, we further investigate the field of interrupt handling.

50
Documentation/kernel-parameters.txt
View File

@ -58,6 +58,7 @@ parameter is applicable:
ISAPNP ISA PnP code is enabled.
ISDN Appropriate ISDN support is enabled.
JOY Appropriate joystick support is enabled.
KGDB Kernel debugger support is enabled.
KVM Kernel Virtual Machine support is enabled.
LIBATA Libata driver is enabled
LP Printer support is enabled.
@ -99,6 +100,7 @@ parameter is applicable:
SWSUSP Software suspend (hibernation) is enabled.
SUSPEND System suspend states are enabled.
FTRACE Function tracing enabled.
TPM TPM drivers are enabled.
TS Appropriate touchscreen support is enabled.
UMS USB Mass Storage support is enabled.
USB USB support is enabled.
@ -151,6 +153,7 @@ and is between 256 and 4096 characters. It is defined in the file
strict -- Be less tolerant of platforms that are not
strictly ACPI specification compliant.
rsdt -- prefer RSDT over (default) XSDT
copy_dsdt -- copy DSDT to memory
See also Documentation/power/pm.txt, pci=noacpi
@ -324,6 +327,8 @@ and is between 256 and 4096 characters. It is defined in the file
they are unmapped. Otherwise they are
flushed before they will be reused, which
is a lot of faster
off - do not initialize any AMD IOMMU found in
the system
amijoy.map= [HW,JOY] Amiga joystick support
Map of devices attached to JOY0DAT and JOY1DAT
@ -708,6 +713,12 @@ and is between 256 and 4096 characters. It is defined in the file
The VGA output is eventually overwritten by the real
console.
ekgdboc= [X86,KGDB] Allow early kernel console debugging
ekgdboc=kbd
This is desgined to be used in conjunction with
the boot argument: earlyprintk=vga
eata= [HW,SCSI]
edd= [EDD]
@ -784,8 +795,12 @@ and is between 256 and 4096 characters. It is defined in the file
as early as possible in order to facilitate early
boot debugging.
ftrace_dump_on_oops
ftrace_dump_on_oops[=orig_cpu]
[FTRACE] will dump the trace buffers on oops.
If no parameter is passed, ftrace will dump
buffers of all CPUs, but if you pass orig_cpu, it will
dump only the buffer of the CPU that triggered the
oops.
ftrace_filter=[function-list]
[FTRACE] Limit the functions traced by the function
@ -1112,10 +1127,26 @@ and is between 256 and 4096 characters. It is defined in the file
use the HighMem zone if it exists, and the Normal
zone if it does not.
kgdboc= [HW] kgdb over consoles.
Requires a tty driver that supports console polling.
(only serial supported for now)
Format: <serial_device>[,baud]
kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
Format: <Controller#>[,poll interval]
The controller # is the number of the ehci usb debug
port as it is probed via PCI. The poll interval is
optional and is the number seconds in between
each poll cycle to the debug port in case you need
the functionality for interrupting the kernel with
gdb or control-c on the dbgp connection. When
not using this parameter you use sysrq-g to break into
the kernel debugger.
kgdboc= [KGDB,HW] kgdb over consoles.
Requires a tty driver that supports console polling,
or a supported polling keyboard driver (non-usb).
Serial only format: <serial_device>[,baud]
keyboard only format: kbd
keyboard and serial format: kbd,<serial_device>[,baud]
kgdbwait [KGDB] Stop kernel execution and enter the
kernel debugger at the earliest opportunity.
kmac= [MIPS] korina ethernet MAC address.
Configure the RouterBoard 532 series on-chip
@ -2610,6 +2641,15 @@ and is between 256 and 4096 characters. It is defined in the file
tp720= [HW,PS2]
tpm_suspend_pcr=[HW,TPM]
Format: integer pcr id
Specify that at suspend time, the tpm driver
should extend the specified pcr with zeros,
as a workaround for some chips which fail to
flush the last written pcr on TPM_SaveState.
This will guarantee that all the other pcrs
are saved.
trace_buf_size=nn[KMG]
[FTRACE] will set tracing buffer size.

12
Documentation/kprobes.txt
View File

@ -165,8 +165,8 @@ the user entry_handler invocation is also skipped.
1.4 How Does Jump Optimization Work?
If you configured your kernel with CONFIG_OPTPROBES=y (currently
this option is supported on x86/x86-64, non-preemptive kernel) and
If your kernel is built with CONFIG_OPTPROBES=y (currently this flag
is automatically set 'y' on x86/x86-64, non-preemptive kernel) and
the "debug.kprobes_optimization" kernel parameter is set to 1 (see
sysctl(8)), Kprobes tries to reduce probe-hit overhead by using a jump
instruction instead of a breakpoint instruction at each probepoint.
@ -271,8 +271,6 @@ tweak the kernel's execution path, you need to suppress optimization,
using one of the following techniques:
- Specify an empty function for the kprobe's post_handler or break_handler.
or
- Config CONFIG_OPTPROBES=n.
or
- Execute 'sysctl -w debug.kprobes_optimization=n'
2. Architectures Supported
@ -307,10 +305,6 @@ it useful to "Compile the kernel with debug info" (CONFIG_DEBUG_INFO),
so you can use "objdump -d -l vmlinux" to see the source-to-object
code mapping.
If you want to reduce probing overhead, set "Kprobes jump optimization
support" (CONFIG_OPTPROBES) to "y". You can find this option under the
"Kprobes" line.
4. API Reference
The Kprobes API includes a "register" function and an "unregister"
@ -332,7 +326,7 @@ occurs during execution of kp->pre_handler or kp->post_handler,
or during single-stepping of the probed instruction, Kprobes calls
kp->fault_handler. Any or all handlers can be NULL. If kp->flags
is set KPROBE_FLAG_DISABLED, that kp will be registered but disabled,
so, it's handlers aren't hit until calling enable_kprobe(kp).
so, its handlers aren't hit until calling enable_kprobe(kp).
NOTE:
1. With the introduction of the "symbol_name" field to struct kprobe,

2
Documentation/laptops/laptop-mode.txt
View File

@ -207,7 +207,7 @@ Tips & Tricks
* Drew Scott Daniels observed: "I don't know why, but when I decrease the number
of colours that my display uses it consumes less battery power. I've seen
this on powerbooks too. I hope that this is a piece of information that
might be useful to the Laptop Mode patch or it's users."
might be useful to the Laptop Mode patch or its users."
* In syslog.conf, you can prefix entries with a dash ``-'' to omit syncing the
file after every logging. When you're using laptop-mode and your disk doesn't

2
Documentation/lguest/lguest.c
View File

@ -263,7 +263,7 @@ static u8 *get_feature_bits(struct device *dev)
* Launcher virtual with an offset.
*
* This can be tough to get your head around, but usually it just means that we
* use these trivial conversion functions when the Guest gives us it's
* use these trivial conversion functions when the Guest gives us its
* "physical" addresses:
*/
static void *from_guest_phys(unsigned long addr)

2
Documentation/md.txt
View File

@ -136,7 +136,7 @@ raid_disks != 0.
Then uninitialized devices can be added with ADD_NEW_DISK. The
structure passed to ADD_NEW_DISK must specify the state of the device
and it's role in the array.
and its role in the array.
Once started with RUN_ARRAY, uninitialized spares can be added with
HOT_ADD_DISK.

2
Documentation/netlabel/lsm_interface.txt
View File

@ -38,7 +38,7 @@ Depending on the exact configuration, translation between the network packet
label and the internal LSM security identifier can be time consuming. The
NetLabel label mapping cache is a caching mechanism which can be used to
sidestep much of this overhead once a mapping has been established. Once the
LSM has received a packet, used NetLabel to decode it's security attributes,
LSM has received a packet, used NetLabel to decode its security attributes,
and translated the security attributes into a LSM internal identifier the LSM
can use the NetLabel caching functions to associate the LSM internal
identifier with the network packet's label. This means that in the future

212
Documentation/networking/caif/Linux-CAIF.txt Normal file
View File

@ -0,0 +1,212 @@
Linux CAIF
===========
copyright (C) ST-Ericsson AB 2010
Author: Sjur Brendeland/ sjur.brandeland@stericsson.com
License terms: GNU General Public License (GPL) version 2
Introduction
------------
CAIF is a MUX protocol used by ST-Ericsson cellular modems for
communication between Modem and host. The host processes can open virtual AT
channels, initiate GPRS Data connections, Video channels and Utility Channels.
The Utility Channels are general purpose pipes between modem and host.
ST-Ericsson modems support a number of transports between modem
and host. Currently, UART and Loopback are available for Linux.
Architecture:
------------
The implementation of CAIF is divided into:
* CAIF Socket Layer, Kernel API, and Net Device.
* CAIF Core Protocol Implementation
* CAIF Link Layer, implemented as NET devices.
RTNL
!
! +------+ +------+ +------+
! +------+! +------+! +------+!
! ! Sock !! !Kernel!! ! Net !!
! ! API !+ ! API !+ ! Dev !+ <- CAIF Client APIs
! +------+ +------! +------+
! ! ! !
! +----------!----------+
! +------+ <- CAIF Protocol Implementation
+-------> ! CAIF !
! Core !
+------+
+--------!--------+
! !
+------+ +-----+
! ! ! TTY ! <- Link Layer (Net Devices)
+------+ +-----+
Using the Kernel API
----------------------
The Kernel API is used for accessing CAIF channels from the
kernel.
The user of the API has to implement two callbacks for receive
and control.
The receive callback gives a CAIF packet as a SKB. The control
callback will
notify of channel initialization complete, and flow-on/flow-
off.
struct caif_device caif_dev = {
.caif_config = {
.name = "MYDEV"
.type = CAIF_CHTY_AT
}
.receive_cb = my_receive,
.control_cb = my_control,
};
caif_add_device(&caif_dev);
caif_transmit(&caif_dev, skb);
See the caif_kernel.h for details about the CAIF kernel API.
I M P L E M E N T A T I O N
===========================
===========================
CAIF Core Protocol Layer
=========================================
CAIF Core layer implements the CAIF protocol as defined by ST-Ericsson.
It implements the CAIF protocol stack in a layered approach, where
each layer described in the specification is implemented as a separate layer.
The architecture is inspired by the design patterns "Protocol Layer" and
"Protocol Packet".
== CAIF structure ==
The Core CAIF implementation contains:
- Simple implementation of CAIF.
- Layered architecture (a la Streams), each layer in the CAIF
specification is implemented in a separate c-file.
- Clients must implement PHY layer to access physical HW
with receive and transmit functions.
- Clients must call configuration function to add PHY layer.
- Clients must implement CAIF layer to consume/produce
CAIF payload with receive and transmit functions.
- Clients must call configuration function to add and connect the
Client layer.
- When receiving / transmitting CAIF Packets (cfpkt), ownership is passed
to the called function (except for framing layers' receive functions
or if a transmit function returns an error, in which case the caller
must free the packet).
Layered Architecture
--------------------
The CAIF protocol can be divided into two parts: Support functions and Protocol
Implementation. The support functions include:
- CFPKT CAIF Packet. Implementation of CAIF Protocol Packet. The
CAIF Packet has functions for creating, destroying and adding content
and for adding/extracting header and trailers to protocol packets.
- CFLST CAIF list implementation.
- CFGLUE CAIF Glue. Contains OS Specifics, such as memory
allocation, endianness, etc.
The CAIF Protocol implementation contains:
- CFCNFG CAIF Configuration layer. Configures the CAIF Protocol
Stack and provides a Client interface for adding Link-Layer and
Driver interfaces on top of the CAIF Stack.
- CFCTRL CAIF Control layer. Encodes and Decodes control messages
such as enumeration and channel setup. Also matches request and
response messages.
- CFSERVL General CAIF Service Layer functionality; handles flow
control and remote shutdown requests.
- CFVEI CAIF VEI layer. Handles CAIF AT Channels on VEI (Virtual
External Interface). This layer encodes/decodes VEI frames.
- CFDGML CAIF Datagram layer. Handles CAIF Datagram layer (IP
traffic), encodes/decodes Datagram frames.
- CFMUX CAIF Mux layer. Handles multiplexing between multiple
physical bearers and multiple channels such as VEI, Datagram, etc.
The MUX keeps track of the existing CAIF Channels and
Physical Instances and selects the apropriate instance based
on Channel-Id and Physical-ID.
- CFFRML CAIF Framing layer. Handles Framing i.e. Frame length
and frame checksum.
- CFSERL CAIF Serial layer. Handles concatenation/split of frames
into CAIF Frames with correct length.
+---------+
| Config |
| CFCNFG |
+---------+
!
+---------+ +---------+ +---------+
| AT | | Control | | Datagram|
| CFVEIL | | CFCTRL | | CFDGML |
+---------+ +---------+ +---------+
\_____________!______________/
!
+---------+
| MUX |
| |
+---------+
_____!_____
/ \
+---------+ +---------+
| CFFRML | | CFFRML |
| Framing | | Framing |
+---------+ +---------+
! !
+---------+ +---------+
| | | Serial |
| | | CFSERL |
+---------+ +---------+
In this layered approach the following "rules" apply.
- All layers embed the same structure "struct cflayer"
- A layer does not depend on any other layer's private data.
- Layers are stacked by setting the pointers
layer->up , layer->dn
- In order to send data upwards, each layer should do
layer->up->receive(layer->up, packet);
- In order to send data downwards, each layer should do
layer->dn->transmit(layer->dn, packet);
Linux Driver Implementation
===========================
Linux GPRS Net Device and CAIF socket are implemented on top of the
CAIF Core protocol. The Net device and CAIF socket have an instance of
'struct cflayer', just like the CAIF Core protocol stack.
Net device and Socket implement the 'receive()' function defined by
'struct cflayer', just like the rest of the CAIF stack. In this way, transmit and
receive of packets is handled as by the rest of the layers: the 'dn->transmit()'
function is called in order to transmit data.
The layer on top of the CAIF Core implementation is
sometimes referred to as the "Client layer".
Configuration of Link Layer
---------------------------
The Link Layer is implemented as Linux net devices (struct net_device).
Payload handling and registration is done using standard Linux mechanisms.
The CAIF Protocol relies on a loss-less link layer without implementing
retransmission. This implies that packet drops must not happen.
Therefore a flow-control mechanism is implemented where the physical
interface can initiate flow stop for all CAIF Channels.

109
Documentation/networking/caif/README Normal file
View File

@ -0,0 +1,109 @@
Copyright (C) ST-Ericsson AB 2010
Author: Sjur Brendeland/ sjur.brandeland@stericsson.com
License terms: GNU General Public License (GPL) version 2
---------------------------------------------------------
=== Start ===
If you have compiled CAIF for modules do:
$modprobe crc_ccitt
$modprobe caif
$modprobe caif_socket
$modprobe chnl_net
=== Preparing the setup with a STE modem ===
If you are working on integration of CAIF you should make sure
that the kernel is built with module support.
There are some things that need to be tweaked to get the host TTY correctly
set up to talk to the modem.
Since the CAIF stack is running in the kernel and we want to use the existing
TTY, we are installing our physical serial driver as a line discipline above
the TTY device.
To achieve this we need to install the N_CAIF ldisc from user space.
The benefit is that we can hook up to any TTY.
The use of Start-of-frame-extension (STX) must also be set as
module parameter "ser_use_stx".
Normally Frame Checksum is always used on UART, but this is also provided as a
module parameter "ser_use_fcs".
$ modprobe caif_serial ser_ttyname=/dev/ttyS0 ser_use_stx=yes
$ ifconfig caif_ttyS0 up
PLEASE NOTE: There is a limitation in Android shell.
It only accepts one argument to insmod/modprobe!
=== Trouble shooting ===
There are debugfs parameters provided for serial communication.
/sys/kernel/debug/caif_serial/<tty-name>/
* ser_state: Prints the bit-mask status where
- 0x02 means SENDING, this is a transient state.
- 0x10 means FLOW_OFF_SENT, i.e. the previous frame has not been sent
and is blocking further send operation. Flow OFF has been propagated
to all CAIF Channels using this TTY.
* tty_status: Prints the bit-mask tty status information
- 0x01 - tty->warned is on.
- 0x02 - tty->low_latency is on.
- 0x04 - tty->packed is on.
- 0x08 - tty->flow_stopped is on.
- 0x10 - tty->hw_stopped is on.
- 0x20 - tty->stopped is on.
* last_tx_msg: Binary blob Prints the last transmitted frame.
This can be printed with
$od --format=x1 /sys/kernel/debug/caif_serial/<tty>/last_rx_msg.
The first two tx messages sent look like this. Note: The initial
byte 02 is start of frame extension (STX) used for re-syncing
upon errors.
- Enumeration:
0000000 02 05 00 00 03 01 d2 02
| | | | | |
STX(1) | | | |
Length(2)| | |
Control Channel(1)
Command:Enumeration(1)
Link-ID(1)
Checksum(2)
- Channel Setup:
0000000 02 07 00 00 00 21 a1 00 48 df
| | | | | | | |
STX(1) | | | | | |
Length(2)| | | | |
Control Channel(1)
Command:Channel Setup(1)
Channel Type(1)
Priority and Link-ID(1)
Endpoint(1)
Checksum(2)
* last_rx_msg: Prints the last transmitted frame.
The RX messages for LinkSetup look almost identical but they have the
bit 0x20 set in the command bit, and Channel Setup has added one byte
before Checksum containing Channel ID.
NOTE: Several CAIF Messages might be concatenated. The maximum debug
buffer size is 128 bytes.
== Error Scenarios:
- last_tx_msg contains channel setup message and last_rx_msg is empty ->
The host seems to be able to send over the UART, at least the CAIF ldisc get
notified that sending is completed.
- last_tx_msg contains enumeration message and last_rx_msg is empty ->
The host is not able to send the message from UART, the tty has not been
able to complete the transmit operation.
- if /sys/kernel/debug/caif_serial/<tty>/tty_status is non-zero there
might be problems transmitting over UART.
E.g. host and modem wiring is not correct you will typically see
tty_status = 0x10 (hw_stopped) and ser_state = 0x10 (FLOW_OFF_SENT).
You will probably see the enumeration message in last_tx_message
and empty last_rx_message.

2
Documentation/networking/ifenslave.c
View File

@ -756,7 +756,7 @@ static int enslave(char *master_ifname, char *slave_ifname)
*/
if (abi_ver < 1) {
/* For old ABI, the master needs to be
* down before setting it's hwaddr
* down before setting its hwaddr
*/
res = set_if_down(master_ifname, master_flags.ifr_flags);
if (res) {

31
Documentation/networking/ip-sysctl.txt
View File

@ -588,6 +588,37 @@ ip_local_port_range - 2 INTEGERS
(i.e. by default) range 1024-4999 is enough to issue up to
2000 connections per second to systems supporting timestamps.
ip_local_reserved_ports - list of comma separated ranges
Specify the ports which are reserved for known third-party
applications. These ports will not be used by automatic port
assignments (e.g. when calling connect() or bind() with port
number 0). Explicit port allocation behavior is unchanged.
The format used for both input and output is a comma separated
list of ranges (e.g. "1,2-4,10-10" for ports 1, 2, 3, 4 and
10). Writing to the file will clear all previously reserved
ports and update the current list with the one given in the
input.
Note that ip_local_port_range and ip_local_reserved_ports
settings are independent and both are considered by the kernel
when determining which ports are available for automatic port
assignments.
You can reserve ports which are not in the current
ip_local_port_range, e.g.:
$ cat /proc/sys/net/ipv4/ip_local_port_range
32000 61000
$ cat /proc/sys/net/ipv4/ip_local_reserved_ports
8080,9148
although this is redundant. However such a setting is useful
if later the port range is changed to a value that will
include the reserved ports.
Default: Empty
ip_nonlocal_bind - BOOLEAN
If set, allows processes to bind() to non-local IP addresses,
which can be quite useful - but may break some applications.

243
Documentation/networking/l2tp.txt
View File

@ -1,44 +1,95 @@
This brief document describes how to use the kernel's PPPoL2TP driver
to provide L2TP functionality. L2TP is a protocol that tunnels one or
more PPP sessions over a UDP tunnel. It is commonly used for VPNs
This document describes how to use the kernel's L2TP drivers to
provide L2TP functionality. L2TP is a protocol that tunnels one or
more sessions over an IP tunnel. It is commonly used for VPNs
(L2TP/IPSec) and by ISPs to tunnel subscriber PPP sessions over an IP
network infrastructure.
network infrastructure. With L2TPv3, it is also useful as a Layer-2
tunneling infrastructure.
Features
========
L2TPv2 (PPP over L2TP (UDP tunnels)).
L2TPv3 ethernet pseudowires.
L2TPv3 PPP pseudowires.
L2TPv3 IP encapsulation.
Netlink sockets for L2TPv3 configuration management.
History
=======
The original pppol2tp driver was introduced in 2.6.23 and provided
L2TPv2 functionality (rfc2661). L2TPv2 is used to tunnel one or more PPP
sessions over a UDP tunnel.
L2TPv3 (rfc3931) changes the protocol to allow different frame types
to be passed over an L2TP tunnel by moving the PPP-specific parts of
the protocol out of the core L2TP packet headers. Each frame type is
known as a pseudowire type. Ethernet, PPP, HDLC, Frame Relay and ATM
pseudowires for L2TP are defined in separate RFC standards. Another
change for L2TPv3 is that it can be carried directly over IP with no
UDP header (UDP is optional). It is also possible to create static
unmanaged L2TPv3 tunnels manually without a control protocol
(userspace daemon) to manage them.
To support L2TPv3, the original pppol2tp driver was split up to
separate the L2TP and PPP functionality. Existing L2TPv2 userspace
apps should be unaffected as the original pppol2tp sockets API is
retained. L2TPv3, however, uses netlink to manage L2TPv3 tunnels and
sessions.
Design
======
The PPPoL2TP driver, drivers/net/pppol2tp.c, provides a mechanism by
which PPP frames carried through an L2TP session are passed through
the kernel's PPP subsystem. The standard PPP daemon, pppd, handles all
PPP interaction with the peer. PPP network interfaces are created for
each local PPP endpoint.
The L2TP protocol separates control and data frames. The L2TP kernel
drivers handle only L2TP data frames; control frames are always
handled by userspace. L2TP control frames carry messages between L2TP
clients/servers and are used to setup / teardown tunnels and
sessions. An L2TP client or server is implemented in userspace.
The L2TP protocol http://www.faqs.org/rfcs/rfc2661.html defines L2TP
control and data frames. L2TP control frames carry messages between
L2TP clients/servers and are used to setup / teardown tunnels and
sessions. An L2TP client or server is implemented in userspace and
will use a regular UDP socket per tunnel. L2TP data frames carry PPP
frames, which may be PPP control or PPP data. The kernel's PPP
Each L2TP tunnel is implemented using a UDP or L2TPIP socket; L2TPIP
provides L2TPv3 IP encapsulation (no UDP) and is implemented using a
new l2tpip socket family. The tunnel socket is typically created by
userspace, though for unmanaged L2TPv3 tunnels, the socket can also be
created by the kernel. Each L2TP session (pseudowire) gets a network
interface instance. In the case of PPP, these interfaces are created
indirectly by pppd using a pppol2tp socket. In the case of ethernet,
the netdevice is created upon a netlink request to create an L2TPv3
ethernet pseudowire.
For PPP, the PPPoL2TP driver, net/l2tp/l2tp_ppp.c, provides a
mechanism by which PPP frames carried through an L2TP session are
passed through the kernel's PPP subsystem. The standard PPP daemon,
pppd, handles all PPP interaction with the peer. PPP network
interfaces are created for each local PPP endpoint. The kernel's PPP
subsystem arranges for PPP control frames to be delivered to pppd,
while data frames are forwarded as usual.
For ethernet, the L2TPETH driver, net/l2tp/l2tp_eth.c, implements a
netdevice driver, managing virtual ethernet devices, one per
pseudowire. These interfaces can be managed using standard Linux tools
such as "ip" and "ifconfig". If only IP frames are passed over the
tunnel, the interface can be given an IP addresses of itself and its
peer. If non-IP frames are to be passed over the tunnel, the interface
can be added to a bridge using brctl. All L2TP datapath protocol
functions are handled by the L2TP core driver.
Each tunnel and session within a tunnel is assigned a unique tunnel_id
and session_id. These ids are carried in the L2TP header of every
control and data packet. The pppol2tp driver uses them to lookup
internal tunnel and/or session contexts. Zero tunnel / session ids are
treated specially - zero ids are never assigned to tunnels or sessions
in the network. In the driver, the tunnel context keeps a pointer to
the tunnel UDP socket. The session context keeps a pointer to the
PPPoL2TP socket, as well as other data that lets the driver interface
to the kernel PPP subsystem.
control and data packet. (Actually, in L2TPv3, the tunnel_id isn't
present in data frames - it is inferred from the IP connection on
which the packet was received.) The L2TP driver uses the ids to lookup
internal tunnel and/or session contexts to determine how to handle the
packet. Zero tunnel / session ids are treated specially - zero ids are
never assigned to tunnels or sessions in the network. In the driver,
the tunnel context keeps a reference to the tunnel UDP or L2TPIP
socket. The session context holds data that lets the driver interface
to the kernel's network frame type subsystems, i.e. PPP, ethernet.
Note that the pppol2tp kernel driver handles only L2TP data frames;
L2TP control frames are simply passed up to userspace in the UDP
tunnel socket. The kernel handles all datapath aspects of the
protocol, including data packet resequencing (if enabled).
Userspace Programming
=====================
There are a number of requirements on the userspace L2TP daemon in
order to use the pppol2tp driver.
For L2TPv2, there are a number of requirements on the userspace L2TP
daemon in order to use the pppol2tp driver.
1. Use a UDP socket per tunnel.
@ -86,6 +137,35 @@ In addition to the standard PPP ioctls, a PPPIOCGL2TPSTATS is provided
to retrieve tunnel and session statistics from the kernel using the
PPPoX socket of the appropriate tunnel or session.
For L2TPv3, userspace must use the netlink API defined in
include/linux/l2tp.h to manage tunnel and session contexts. The
general procedure to create a new L2TP tunnel with one session is:-
1. Open a GENL socket using L2TP_GENL_NAME for configuring the kernel
using netlink.
2. Create a UDP or L2TPIP socket for the tunnel.
3. Create a new L2TP tunnel using a L2TP_CMD_TUNNEL_CREATE
request. Set attributes according to desired tunnel parameters,
referencing the UDP or L2TPIP socket created in the previous step.
4. Create a new L2TP session in the tunnel using a
L2TP_CMD_SESSION_CREATE request.
The tunnel and all of its sessions are closed when the tunnel socket
is closed. The netlink API may also be used to delete sessions and
tunnels. Configuration and status info may be set or read using netlink.
The L2TP driver also supports static (unmanaged) L2TPv3 tunnels. These
are where there is no L2TP control message exchange with the peer to
setup the tunnel; the tunnel is configured manually at each end of the
tunnel. There is no need for an L2TP userspace application in this
case -- the tunnel socket is created by the kernel and configured
using parameters sent in the L2TP_CMD_TUNNEL_CREATE netlink
request. The "ip" utility of iproute2 has commands for managing static
L2TPv3 tunnels; do "ip l2tp help" for more information.
Debugging
=========
@ -102,6 +182,69 @@ PPPOL2TP_MSG_CONTROL userspace - kernel interface
PPPOL2TP_MSG_SEQ sequence numbers handling
PPPOL2TP_MSG_DATA data packets
If enabled, files under a l2tp debugfs directory can be used to dump
kernel state about L2TP tunnels and sessions. To access it, the
debugfs filesystem must first be mounted.
# mount -t debugfs debugfs /debug
Files under the l2tp directory can then be accessed.
# cat /debug/l2tp/tunnels
The debugfs files should not be used by applications to obtain L2TP
state information because the file format is subject to change. It is
implemented to provide extra debug information to help diagnose
problems.) Users should use the netlink API.
/proc/net/pppol2tp is also provided for backwards compaibility with
the original pppol2tp driver. It lists information about L2TPv2
tunnels and sessions only. Its use is discouraged.
Unmanaged L2TPv3 Tunnels
========================
Some commercial L2TP products support unmanaged L2TPv3 ethernet
tunnels, where there is no L2TP control protocol; tunnels are
configured at each side manually. New commands are available in
iproute2's ip utility to support this.
To create an L2TPv3 ethernet pseudowire between local host 192.168.1.1
and peer 192.168.1.2, using IP addresses 10.5.1.1 and 10.5.1.2 for the
tunnel endpoints:-
# modprobe l2tp_eth
# modprobe l2tp_netlink
# ip l2tp add tunnel tunnel_id 1 peer_tunnel_id 1 udp_sport 5000 \
udp_dport 5000 encap udp local 192.168.1.1 remote 192.168.1.2
# ip l2tp add session tunnel_id 1 session_id 1 peer_session_id 1
# ifconfig -a
# ip addr add 10.5.1.2/32 peer 10.5.1.1/32 dev l2tpeth0
# ifconfig l2tpeth0 up
Choose IP addresses to be the address of a local IP interface and that
of the remote system. The IP addresses of the l2tpeth0 interface can be
anything suitable.
Repeat the above at the peer, with ports, tunnel/session ids and IP
addresses reversed. The tunnel and session IDs can be any non-zero
32-bit number, but the values must be reversed at the peer.
Host 1 Host2
udp_sport=5000 udp_sport=5001
udp_dport=5001 udp_dport=5000
tunnel_id=42 tunnel_id=45
peer_tunnel_id=45 peer_tunnel_id=42
session_id=128 session_id=5196755
peer_session_id=5196755 peer_session_id=128
When done at both ends of the tunnel, it should be possible to send
data over the network. e.g.
# ping 10.5.1.1
Sample Userspace Code
=====================
@ -158,12 +301,48 @@ Sample Userspace Code
}
return 0;
Miscellaneous
============
Internal Implementation
=======================
The PPPoL2TP driver was developed as part of the OpenL2TP project by
The driver keeps a struct l2tp_tunnel context per L2TP tunnel and a
struct l2tp_session context for each session. The l2tp_tunnel is
always associated with a UDP or L2TP/IP socket and keeps a list of
sessions in the tunnel. The l2tp_session context keeps kernel state
about the session. It has private data which is used for data specific
to the session type. With L2TPv2, the session always carried PPP
traffic. With L2TPv3, the session can also carry ethernet frames
(ethernet pseudowire) or other data types such as ATM, HDLC or Frame
Relay.
When a tunnel is first opened, the reference count on the socket is
increased using sock_hold(). This ensures that the kernel socket
cannot be removed while L2TP's data structures reference it.
Some L2TP sessions also have a socket (PPP pseudowires) while others
do not (ethernet pseudowires). We can't use the socket reference count
as the reference count for session contexts. The L2TP implementation
therefore has its own internal reference counts on the session
contexts.
To Do
=====
Add L2TP tunnel switching support. This would route tunneled traffic
from one L2TP tunnel into another. Specified in
http://tools.ietf.org/html/draft-ietf-l2tpext-tunnel-switching-08
Add L2TPv3 VLAN pseudowire support.
Add L2TPv3 IP pseudowire support.
Add L2TPv3 ATM pseudowire support.
Miscellaneous
=============
The L2TP drivers were developed as part of the OpenL2TP project by
Katalix Systems Ltd. OpenL2TP is a full-featured L2TP client / server,
designed from the ground up to have the L2TP datapath in the
kernel. The project also implemented the pppol2tp plugin for pppd
which allows pppd to use the kernel driver. Details can be found at
http://openl2tp.sourceforge.net.
http://www.openl2tp.org.

4
Documentation/networking/packet_mmap.txt
View File

@ -100,7 +100,7 @@ by the kernel.
The destruction of the socket and all associated resources
is done by a simple call to close(fd).
Next I will describe PACKET_MMAP settings and it's constraints,
Next I will describe PACKET_MMAP settings and its constraints,
also the mapping of the circular buffer in the user process and
the use of this buffer.
@ -432,7 +432,7 @@ TP_STATUS_LOSING : indicates there were packet drops from last time
the PACKET_STATISTICS option.
TP_STATUS_CSUMNOTREADY: currently it's used for outgoing IP packets which
it's checksum will be done in hardware. So while
its checksum will be done in hardware. So while
reading the packet we should not try to check the
checksum.

16
Documentation/networking/x25-iface.txt
View File

@ -20,23 +20,23 @@ the rest of the skbuff, if any more information does exist.
Packet Layer to Device Driver
-----------------------------
First Byte = 0x00
First Byte = 0x00 (X25_IFACE_DATA)
This indicates that the rest of the skbuff contains data to be transmitted
over the LAPB link. The LAPB link should already exist before any data is
passed down.
First Byte = 0x01
First Byte = 0x01 (X25_IFACE_CONNECT)
Establish the LAPB link. If the link is already established then the connect
confirmation message should be returned as soon as possible.
First Byte = 0x02
First Byte = 0x02 (X25_IFACE_DISCONNECT)
Terminate the LAPB link. If it is already disconnected then the disconnect
confirmation message should be returned as soon as possible.
First Byte = 0x03
First Byte = 0x03 (X25_IFACE_PARAMS)
LAPB parameters. To be defined.
@ -44,22 +44,22 @@ LAPB parameters. To be defined.
Device Driver to Packet Layer
-----------------------------
First Byte = 0x00
First Byte = 0x00 (X25_IFACE_DATA)
This indicates that the rest of the skbuff contains data that has been
received over the LAPB link.
First Byte = 0x01
First Byte = 0x01 (X25_IFACE_CONNECT)
LAPB link has been established. The same message is used for both a LAPB
link connect_confirmation and a connect_indication.
First Byte = 0x02
First Byte = 0x02 (X25_IFACE_DISCONNECT)
LAPB link has been terminated. This same message is used for both a LAPB
link disconnect_confirmation and a disconnect_indication.
First Byte = 0x03
First Byte = 0x03 (X25_IFACE_PARAMS)
LAPB parameters. To be defined.

107
Documentation/padata.txt Normal file
View File

@ -0,0 +1,107 @@
The padata parallel execution mechanism
Last updated for 2.6.34
Padata is a mechanism by which the kernel can farm work out to be done in
parallel on multiple CPUs while retaining the ordering of tasks. It was
developed for use with the IPsec code, which needs to be able to perform
encryption and decryption on large numbers of packets without reordering
those packets. The crypto developers made a point of writing padata in a
sufficiently general fashion that it could be put to other uses as well.
The first step in using padata is to set up a padata_instance structure for
overall control of how tasks are to be run:
#include <linux/padata.h>
struct padata_instance *padata_alloc(const struct cpumask *cpumask,
struct workqueue_struct *wq);
The cpumask describes which processors will be used to execute work
submitted to this instance. The workqueue wq is where the work will
actually be done; it should be a multithreaded queue, naturally.
There are functions for enabling and disabling the instance:
void padata_start(struct padata_instance *pinst);
void padata_stop(struct padata_instance *pinst);
These functions literally do nothing beyond setting or clearing the
"padata_start() was called" flag; if that flag is not set, other functions
will refuse to work.
The list of CPUs to be used can be adjusted with these functions:
int padata_set_cpumask(struct padata_instance *pinst,
cpumask_var_t cpumask);
int padata_add_cpu(struct padata_instance *pinst, int cpu);
int padata_remove_cpu(struct padata_instance *pinst, int cpu);
Changing the CPU mask has the look of an expensive operation, though, so it
probably should not be done with great frequency.
Actually submitting work to the padata instance requires the creation of a
padata_priv structure:
struct padata_priv {
/* Other stuff here... */
void (*parallel)(struct padata_priv *padata);
void (*serial)(struct padata_priv *padata);
};
This structure will almost certainly be embedded within some larger
structure specific to the work to be done. Most its fields are private to
padata, but the structure should be zeroed at initialization time, and the
parallel() and serial() functions should be provided. Those functions will
be called in the process of getting the work done as we will see
momentarily.
The submission of work is done with:
int padata_do_parallel(struct padata_instance *pinst,
struct padata_priv *padata, int cb_cpu);
The pinst and padata structures must be set up as described above; cb_cpu
specifies which CPU will be used for the final callback when the work is
done; it must be in the current instance's CPU mask. The return value from
padata_do_parallel() is a little strange; zero is an error return
indicating that the caller forgot the padata_start() formalities. -EBUSY
means that somebody, somewhere else is messing with the instance's CPU
mask, while -EINVAL is a complaint about cb_cpu not being in that CPU mask.
If all goes well, this function will return -EINPROGRESS, indicating that
the work is in progress.
Each task submitted to padata_do_parallel() will, in turn, be passed to
exactly one call to the above-mentioned parallel() function, on one CPU, so
true parallelism is achieved by submitting multiple tasks. Despite the
fact that the workqueue is used to make these calls, parallel() is run with
software interrupts disabled and thus cannot sleep. The parallel()
function gets the padata_priv structure pointer as its lone parameter;
information about the actual work to be done is probably obtained by using
container_of() to find the enclosing structure.
Note that parallel() has no return value; the padata subsystem assumes that
parallel() will take responsibility for the task from this point. The work
need not be completed during this call, but, if parallel() leaves work
outstanding, it should be prepared to be called again with a new job before
the previous one completes. When a task does complete, parallel() (or
whatever function actually finishes the job) should inform padata of the
fact with a call to:
void padata_do_serial(struct padata_priv *padata);
At some point in the future, padata_do_serial() will trigger a call to the
serial() function in the padata_priv structure. That call will happen on
the CPU requested in the initial call to padata_do_parallel(); it, too, is
done through the workqueue, but with local software interrupts disabled.
Note that this call may be deferred for a while since the padata code takes
pains to ensure that tasks are completed in the order in which they were
submitted.
The one remaining function in the padata API should be called to clean up
when a padata instance is no longer needed:
void padata_free(struct padata_instance *pinst);
This function will busy-wait while any remaining tasks are completed, so it
might be best not to call it while there is work outstanding. Shutting
down the workqueue, if necessary, should be done separately.

13
Documentation/pcmcia/driver-changes.txt
View File

@ -1,4 +1,17 @@
This file details changes in 2.6 which affect PCMCIA card driver authors:
* No dev_node_t (as of 2.6.35)
There is no more need to fill out a "dev_node_t" structure.
* New IRQ request rules (as of 2.6.35)
Instead of the old pcmcia_request_irq() interface, drivers may now
choose between:
- calling request_irq/free_irq directly. Use the IRQ from *p_dev->irq.
- use pcmcia_request_irq(p_dev, handler_t); the PCMCIA core will
clean up automatically on calls to pcmcia_disable_device() or
device ejection.
- drivers still not capable of IRQF_SHARED (or not telling us so) may
use the deprecated pcmcia_request_exclusive_irq() for the time
being; they might receive a shared IRQ nonetheless.
* no cs_error / CS_CHECK / CONFIG_PCMCIA_DEBUG (as of 2.6.33)
Instead of the cs_error() callback or the CS_CHECK() macro, please use

815
Documentation/power/devices.txt
View File

@ -1,7 +1,13 @@
Device Power Management
Copyright (c) 2010 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
Copyright (c) 2010 Alan Stern <stern@rowland.harvard.edu>
Most of the code in Linux is device drivers, so most of the Linux power
management code is also driver-specific. Most drivers will do very little;
others, especially for platforms with small batteries (like cell phones),
will do a lot.
management (PM) code is also driver-specific. Most drivers will do very
little; others, especially for platforms with small batteries (like cell
phones), will do a lot.
This writeup gives an overview of how drivers interact with system-wide
power management goals, emphasizing the models and interfaces that are
@ -15,9 +21,10 @@ Drivers will use one or both of these models to put devices into low-power
states:
System Sleep model:
Drivers can enter low power states as part of entering system-wide
low-power states like "suspend-to-ram", or (mostly for systems with
disks) "hibernate" (suspend-to-disk).
Drivers can enter low-power states as part of entering system-wide
low-power states like "suspend" (also known as "suspend-to-RAM"), or
(mostly for systems with disks) "hibernation" (also known as
"suspend-to-disk").
This is something that device, bus, and class drivers collaborate on
by implementing various role-specific suspend and resume methods to
@ -25,33 +32,41 @@ states:
them without loss of data.
Some drivers can manage hardware wakeup events, which make the system
leave that low-power state. This feature may be disabled using the
relevant /sys/devices/.../power/wakeup file; enabling it may cost some
power usage, but let the whole system enter low power states more often.
leave the low-power state. This feature may be enabled or disabled
using the relevant /sys/devices/.../power/wakeup file (for Ethernet
drivers the ioctl interface used by ethtool may also be used for this
purpose); enabling it may cost some power usage, but let the whole
system enter low-power states more often.
Runtime Power Management model:
Drivers may also enter low power states while the system is running,
independently of other power management activity. Upstream drivers
will normally not know (or care) if the device is in some low power
state when issuing requests; the driver will auto-resume anything
that's needed when it gets a request.
Devices may also be put into low-power states while the system is
running, independently of other power management activity in principle.
However, devices are not generally independent of each other (for
example, a parent device cannot be suspended unless all of its child
devices have been suspended). Moreover, depending on the bus type the
device is on, it may be necessary to carry out some bus-specific
operations on the device for this purpose. Devices put into low power
states at run time may require special handling during system-wide power
transitions (suspend or hibernation).
This doesn't have, or need much infrastructure; it's just something you
should do when writing your drivers. For example, clk_disable() unused
clocks as part of minimizing power drain for currently-unused hardware.
Of course, sometimes clusters of drivers will collaborate with each
other, which could involve task-specific power management.
For these reasons not only the device driver itself, but also the
appropriate subsystem (bus type, device type or device class) driver and
the PM core are involved in runtime power management. As in the system
sleep power management case, they need to collaborate by implementing
various role-specific suspend and resume methods, so that the hardware
is cleanly powered down and reactivated without data or service loss.
There's not a lot to be said about those low power states except that they
are very system-specific, and often device-specific. Also, that if enough
drivers put themselves into low power states (at "runtime"), the effect may be
the same as entering some system-wide low-power state (system sleep) ... and
that synergies exist, so that several drivers using runtime pm might put the
system into a state where even deeper power saving options are available.
There's not a lot to be said about those low-power states except that they are
very system-specific, and often device-specific. Also, that if enough devices
have been put into low-power states (at runtime), the effect may be very similar
to entering some system-wide low-power state (system sleep) ... and that
synergies exist, so that several drivers using runtime PM might put the system
into a state where even deeper power saving options are available.
Most suspended devices will have quiesced all I/O: no more DMA or irqs, no
more data read or written, and requests from upstream drivers are no longer
accepted. A given bus or platform may have different requirements though.
Most suspended devices will have quiesced all I/O: no more DMA or IRQs (except
for wakeup events), no more data read or written, and requests from upstream
drivers are no longer accepted. A given bus or platform may have different
requirements though.
Examples of hardware wakeup events include an alarm from a real time clock,
network wake-on-LAN packets, keyboard or mouse activity, and media insertion
@ -60,129 +75,152 @@ or removal (for PCMCIA, MMC/SD, USB, and so on).
Interfaces for Entering System Sleep States
===========================================
Most of the programming interfaces a device driver needs to know about
relate to that first model: entering a system-wide low power state,
rather than just minimizing power consumption by one device.
There are programming interfaces provided for subsystems (bus type, device type,
device class) and device drivers to allow them to participate in the power
management of devices they are concerned with. These interfaces cover both
system sleep and runtime power management.
Bus Driver Methods
------------------
The core methods to suspend and resume devices reside in struct bus_type.
These are mostly of interest to people writing infrastructure for busses
like PCI or USB, or because they define the primitives that device drivers
may need to apply in domain-specific ways to their devices:
Device Power Management Operations
----------------------------------
Device power management operations, at the subsystem level as well as at the
device driver level, are implemented by defining and populating objects of type
struct dev_pm_ops:
struct bus_type {
...
int (*suspend)(struct device *dev, pm_message_t state);
int (*resume)(struct device *dev);
struct dev_pm_ops {
int (*prepare)(struct device *dev);
void (*complete)(struct device *dev);
int (*suspend)(struct device *dev);
int (*resume)(struct device *dev);
int (*freeze)(struct device *dev);
int (*thaw)(struct device *dev);
int (*poweroff)(struct device *dev);
int (*restore)(struct device *dev);
int (*suspend_noirq)(struct device *dev);
int (*resume_noirq)(struct device *dev);
int (*freeze_noirq)(struct device *dev);
int (*thaw_noirq)(struct device *dev);
int (*poweroff_noirq)(struct device *dev);
int (*restore_noirq)(struct device *dev);
int (*runtime_suspend)(struct device *dev);
int (*runtime_resume)(struct device *dev);
int (*runtime_idle)(struct device *dev);
};
Bus drivers implement those methods as appropriate for the hardware and
the drivers using it; PCI works differently from USB, and so on. Not many
people write bus drivers; most driver code is a "device driver" that
builds on top of bus-specific framework code.
This structure is defined in include/linux/pm.h and the methods included in it
are also described in that file. Their roles will be explained in what follows.
For now, it should be sufficient to remember that the last three methods are
specific to runtime power management while the remaining ones are used during
system-wide power transitions.
There also is a deprecated "old" or "legacy" interface for power management
operations available at least for some subsystems. This approach does not use
struct dev_pm_ops objects and it is suitable only for implementing system sleep
power management methods. Therefore it is not described in this document, so
please refer directly to the source code for more information about it.
Subsystem-Level Methods
-----------------------
The core methods to suspend and resume devices reside in struct dev_pm_ops
pointed to by the pm member of struct bus_type, struct device_type and
struct class. They are mostly of interest to the people writing infrastructure
for buses, like PCI or USB, or device type and device class drivers.
Bus drivers implement these methods as appropriate for the hardware and the
drivers using it; PCI works differently from USB, and so on. Not many people
write subsystem-level drivers; most driver code is a "device driver" that builds
on top of bus-specific framework code.
For more information on these driver calls, see the description later;
they are called in phases for every device, respecting the parent-child
sequencing in the driver model tree. Note that as this is being written,
only the suspend() and resume() are widely available; not many bus drivers
leverage all of those phases, or pass them down to lower driver levels.
sequencing in the driver model tree.
/sys/devices/.../power/wakeup files
-----------------------------------
All devices in the driver model have two flags to control handling of
wakeup events, which are hardware signals that can force the device and/or
system out of a low power state. These are initialized by bus or device
driver code using device_init_wakeup(dev,can_wakeup).
All devices in the driver model have two flags to control handling of wakeup
events (hardware signals that can force the device and/or system out of a low
power state). These flags are initialized by bus or device driver code using
device_set_wakeup_capable() and device_set_wakeup_enable(), defined in
include/linux/pm_wakeup.h.
The "can_wakeup" flag just records whether the device (and its driver) can
physically support wakeup events. When that flag is clear, the sysfs
"wakeup" file is empty, and device_may_wakeup() returns false.
physically support wakeup events. The device_set_wakeup_capable() routine
affects this flag. The "should_wakeup" flag controls whether the device should
try to use its wakeup mechanism. device_set_wakeup_enable() affects this flag;
for the most part drivers should not change its value. The initial value of
should_wakeup is supposed to be false for the majority of devices; the major
exceptions are power buttons, keyboards, and Ethernet adapters whose WoL
(wake-on-LAN) feature has been set up with ethtool.
For devices that can issue wakeup events, a separate flag controls whether
that device should try to use its wakeup mechanism. The initial value of
device_may_wakeup() will be true, so that the device's "wakeup" file holds
the value "enabled". Userspace can change that to "disabled" so that
device_may_wakeup() returns false; or change it back to "enabled" (so that
it returns true again).
Whether or not a device is capable of issuing wakeup events is a hardware
matter, and the kernel is responsible for keeping track of it. By contrast,
whether or not a wakeup-capable device should issue wakeup events is a policy
decision, and it is managed by user space through a sysfs attribute: the
power/wakeup file. User space can write the strings "enabled" or "disabled" to
set or clear the should_wakeup flag, respectively. Reads from the file will
return the corresponding string if can_wakeup is true, but if can_wakeup is
false then reads will return an empty string, to indicate that the device
doesn't support wakeup events. (But even though the file appears empty, writes
will still affect the should_wakeup flag.)
The device_may_wakeup() routine returns true only if both flags are set.
Drivers should check this routine when putting devices in a low-power state
during a system sleep transition, to see whether or not to enable the devices'
wakeup mechanisms. However for runtime power management, wakeup events should
be enabled whenever the device and driver both support them, regardless of the
should_wakeup flag.
EXAMPLE: PCI Device Driver Methods
-----------------------------------
PCI framework software calls these methods when the PCI device driver bound
to a device device has provided them:
/sys/devices/.../power/control files
------------------------------------
Each device in the driver model has a flag to control whether it is subject to
runtime power management. This flag, called runtime_auto, is initialized by the
bus type (or generally subsystem) code using pm_runtime_allow() or
pm_runtime_forbid(); the default is to allow runtime power management.
struct pci_driver {
...
int (*suspend)(struct pci_device *pdev, pm_message_t state);
int (*suspend_late)(struct pci_device *pdev, pm_message_t state);
The setting can be adjusted by user space by writing either "on" or "auto" to
the device's power/control sysfs file. Writing "auto" calls pm_runtime_allow(),
setting the flag and allowing the device to be runtime power-managed by its
driver. Writing "on" calls pm_runtime_forbid(), clearing the flag, returning
the device to full power if it was in a low-power state, and preventing the
device from being runtime power-managed. User space can check the current value
of the runtime_auto flag by reading the file.
int (*resume_early)(struct pci_device *pdev);
int (*resume)(struct pci_device *pdev);
};
The device's runtime_auto flag has no effect on the handling of system-wide
power transitions. In particular, the device can (and in the majority of cases
should and will) be put into a low-power state during a system-wide transition
to a sleep state even though its runtime_auto flag is clear.
Drivers will implement those methods, and call PCI-specific procedures
like pci_set_power_state(), pci_enable_wake(), pci_save_state(), and
pci_restore_state() to manage PCI-specific mechanisms. (PCI config space
could be saved during driver probe, if it weren't for the fact that some
systems rely on userspace tweaking using setpci.) Devices are suspended
before their bridges enter low power states, and likewise bridges resume
before their devices.
For more information about the runtime power management framework, refer to
Documentation/power/runtime_pm.txt.
Upper Layers of Driver Stacks
-----------------------------
Device drivers generally have at least two interfaces, and the methods
sketched above are the ones which apply to the lower level (nearer PCI, USB,
or other bus hardware). The network and block layers are examples of upper
level interfaces, as is a character device talking to userspace.
Power management requests normally need to flow through those upper levels,
which often use domain-oriented requests like "blank that screen". In
some cases those upper levels will have power management intelligence that
relates to end-user activity, or other devices that work in cooperation.
When those interfaces are structured using class interfaces, there is a
standard way to have the upper layer stop issuing requests to a given
class device (and restart later):
struct class {
...
int (*suspend)(struct device *dev, pm_message_t state);
int (*resume)(struct device *dev);
};
Those calls are issued in specific phases of the process by which the
system enters a low power "suspend" state, or resumes from it.
Calling Drivers to Enter System Sleep States
============================================
When the system enters a low power state, each device's driver is asked
to suspend the device by putting it into state compatible with the target
Calling Drivers to Enter and Leave System Sleep States
======================================================
When the system goes into a sleep state, each device's driver is asked to
suspend the device by putting it into a state compatible with the target
system state. That's usually some version of "off", but the details are
system-specific. Also, wakeup-enabled devices will usually stay partly
functional in order to wake the system.
When the system leaves that low power state, the device's driver is asked
to resume it. The suspend and resume operations always go together, and
both are multi-phase operations.
When the system leaves that low-power state, the device's driver is asked to
resume it by returning it to full power. The suspend and resume operations
always go together, and both are multi-phase operations.
For simple drivers, suspend might quiesce the device using the class code
and then turn its hardware as "off" as possible with late_suspend. The
For simple drivers, suspend might quiesce the device using class code
and then turn its hardware as "off" as possible during suspend_noirq. The
matching resume calls would then completely reinitialize the hardware
before reactivating its class I/O queues.
More power-aware drivers drivers will use more than one device low power
state, either at runtime or during system sleep states, and might trigger
system wakeup events.
More power-aware drivers might prepare the devices for triggering system wakeup
events.
Call Sequence Guarantees
------------------------
To ensure that bridges and similar links needed to talk to a device are
To ensure that bridges and similar links needing to talk to a device are
available when the device is suspended or resumed, the device tree is
walked in a bottom-up order to suspend devices. A top-down order is
used to resume those devices.
@ -194,67 +232,310 @@ its parent; and can't be removed or suspended after that parent.
The policy is that the device tree should match hardware bus topology.
(Or at least the control bus, for devices which use multiple busses.)
In particular, this means that a device registration may fail if the parent of
the device is suspending (ie. has been chosen by the PM core as the next
the device is suspending (i.e. has been chosen by the PM core as the next
device to suspend) or has already suspended, as well as after all of the other
devices have been suspended. Device drivers must be prepared to cope with such
situations.
Suspending Devices
------------------
Suspending a given device is done in several phases. Suspending the
system always includes every phase, executing calls for every device
before the next phase begins. Not all busses or classes support all
these callbacks; and not all drivers use all the callbacks.
System Power Management Phases
------------------------------
Suspending or resuming the system is done in several phases. Different phases
are used for standby or memory sleep states ("suspend-to-RAM") and the
hibernation state ("suspend-to-disk"). Each phase involves executing callbacks
for every device before the next phase begins. Not all busses or classes
support all these callbacks and not all drivers use all the callbacks. The
various phases always run after tasks have been frozen and before they are
unfrozen. Furthermore, the *_noirq phases run at a time when IRQ handlers have
been disabled (except for those marked with the IRQ_WAKEUP flag).
The phases are seen by driver notifications issued in this order:
Most phases use bus, type, and class callbacks (that is, methods defined in
dev->bus->pm, dev->type->pm, and dev->class->pm). The prepare and complete
phases are exceptions; they use only bus callbacks. When multiple callbacks
are used in a phase, they are invoked in the order: <class, type, bus> during
power-down transitions and in the opposite order during power-up transitions.
For example, during the suspend phase the PM core invokes
1 class.suspend(dev, message) is called after tasks are frozen, for
devices associated with a class that has such a method. This
method may sleep.
dev->class->pm.suspend(dev);
dev->type->pm.suspend(dev);
dev->bus->pm.suspend(dev);
Since I/O activity usually comes from such higher layers, this is
a good place to quiesce all drivers of a given type (and keep such
code out of those drivers).
before moving on to the next device, whereas during the resume phase the core
invokes
2 bus.suspend(dev, message) is called next. This method may sleep,
and is often morphed into a device driver call with bus-specific
parameters and/or rules.
dev->bus->pm.resume(dev);
dev->type->pm.resume(dev);
dev->class->pm.resume(dev);
This call should handle parts of device suspend logic that require
sleeping. It probably does work to quiesce the device which hasn't
been abstracted into class.suspend().
These callbacks may in turn invoke device- or driver-specific methods stored in
dev->driver->pm, but they don't have to.
The pm_message_t parameter is currently used to refine those semantics
(described later).
At the end of those phases, drivers should normally have stopped all I/O
transactions (DMA, IRQs), saved enough state that they can re-initialize
or restore previous state (as needed by the hardware), and placed the
device into a low-power state. On many platforms they will also use
clk_disable() to gate off one or more clock sources; sometimes they will
also switch off power supplies, or reduce voltages. Drivers which have
runtime PM support may already have performed some or all of the steps
needed to prepare for the upcoming system sleep state.
Entering System Suspend
-----------------------
When the system goes into the standby or memory sleep state, the phases are:
When any driver sees that its device_can_wakeup(dev), it should make sure
to use the relevant hardware signals to trigger a system wakeup event.
For example, enable_irq_wake() might identify GPIO signals hooked up to
a switch or other external hardware, and pci_enable_wake() does something
similar for PCI's PME# signal.
prepare, suspend, suspend_noirq.
If a driver (or bus, or class) fails it suspend method, the system won't
enter the desired low power state; it will resume all the devices it's
suspended so far.
1. The prepare phase is meant to prevent races by preventing new devices
from being registered; the PM core would never know that all the
children of a device had been suspended if new children could be
registered at will. (By contrast, devices may be unregistered at any
time.) Unlike the other suspend-related phases, during the prepare
phase the device tree is traversed top-down.
Note that drivers may need to perform different actions based on the target
system lowpower/sleep state. At this writing, there are only platform
specific APIs through which drivers could determine those target states.
The prepare phase uses only a bus callback. After the callback method
returns, no new children may be registered below the device. The method
may also prepare the device or driver in some way for the upcoming
system power transition, but it should not put the device into a
low-power state.
2. The suspend methods should quiesce the device to stop it from performing
I/O. They also may save the device registers and put it into the
appropriate low-power state, depending on the bus type the device is on,
and they may enable wakeup events.
3. The suspend_noirq phase occurs after IRQ handlers have been disabled,
which means that the driver's interrupt handler will not be called while
the callback method is running. The methods should save the values of
the device's registers that weren't saved previously and finally put the
device into the appropriate low-power state.
The majority of subsystems and device drivers need not implement this
callback. However, bus types allowing devices to share interrupt
vectors, like PCI, generally need it; otherwise a driver might encounter
an error during the suspend phase by fielding a shared interrupt
generated by some other device after its own device had been set to low
power.
At the end of these phases, drivers should have stopped all I/O transactions
(DMA, IRQs), saved enough state that they can re-initialize or restore previous
state (as needed by the hardware), and placed the device into a low-power state.
On many platforms they will gate off one or more clock sources; sometimes they
will also switch off power supplies or reduce voltages. (Drivers supporting
runtime PM may already have performed some or all of these steps.)
If device_may_wakeup(dev) returns true, the device should be prepared for
generating hardware wakeup signals to trigger a system wakeup event when the
system is in the sleep state. For example, enable_irq_wake() might identify
GPIO signals hooked up to a switch or other external hardware, and
pci_enable_wake() does something similar for the PCI PME signal.
If any of these callbacks returns an error, the system won't enter the desired
low-power state. Instead the PM core will unwind its actions by resuming all
the devices that were suspended.
Leaving System Suspend
----------------------
When resuming from standby or memory sleep, the phases are:
resume_noirq, resume, complete.
1. The resume_noirq callback methods should perform any actions needed
before the driver's interrupt handlers are invoked. This generally
means undoing the actions of the suspend_noirq phase. If the bus type
permits devices to share interrupt vectors, like PCI, the method should
bring the device and its driver into a state in which the driver can
recognize if the device is the source of incoming interrupts, if any,
and handle them correctly.
For example, the PCI bus type's ->pm.resume_noirq() puts the device into
the full-power state (D0 in the PCI terminology) and restores the
standard configuration registers of the device. Then it calls the
device driver's ->pm.resume_noirq() method to perform device-specific
actions.
2. The resume methods should bring the the device back to its operating
state, so that it can perform normal I/O. This generally involves
undoing the actions of the suspend phase.
3. The complete phase uses only a bus callback. The method should undo the
actions of the prepare phase. Note, however, that new children may be
registered below the device as soon as the resume callbacks occur; it's
not necessary to wait until the complete phase.
At the end of these phases, drivers should be as functional as they were before
suspending: I/O can be performed using DMA and IRQs, and the relevant clocks are
gated on. Even if the device was in a low-power state before the system sleep
because of runtime power management, afterwards it should be back in its
full-power state. There are multiple reasons why it's best to do this; they are
discussed in more detail in Documentation/power/runtime_pm.txt.
However, the details here may again be platform-specific. For example,
some systems support multiple "run" states, and the mode in effect at
the end of resume might not be the one which preceded suspension.
That means availability of certain clocks or power supplies changed,
which could easily affect how a driver works.
Drivers need to be able to handle hardware which has been reset since the
suspend methods were called, for example by complete reinitialization.
This may be the hardest part, and the one most protected by NDA'd documents
and chip errata. It's simplest if the hardware state hasn't changed since
the suspend was carried out, but that can't be guaranteed (in fact, it ususally
is not the case).
Drivers must also be prepared to notice that the device has been removed
while the system was powered down, whenever that's physically possible.
PCMCIA, MMC, USB, Firewire, SCSI, and even IDE are common examples of busses
where common Linux platforms will see such removal. Details of how drivers
will notice and handle such removals are currently bus-specific, and often
involve a separate thread.
These callbacks may return an error value, but the PM core will ignore such
errors since there's nothing it can do about them other than printing them in
the system log.
Entering Hibernation
--------------------
Hibernating the system is more complicated than putting it into the standby or
memory sleep state, because it involves creating and saving a system image.
Therefore there are more phases for hibernation, with a different set of
callbacks. These phases always run after tasks have been frozen and memory has
been freed.
The general procedure for hibernation is to quiesce all devices (freeze), create
an image of the system memory while everything is stable, reactivate all
devices (thaw), write the image to permanent storage, and finally shut down the
system (poweroff). The phases used to accomplish this are:
prepare, freeze, freeze_noirq, thaw_noirq, thaw, complete,
prepare, poweroff, poweroff_noirq
1. The prepare phase is discussed in the "Entering System Suspend" section
above.
2. The freeze methods should quiesce the device so that it doesn't generate
IRQs or DMA, and they may need to save the values of device registers.
However the device does not have to be put in a low-power state, and to
save time it's best not to do so. Also, the device should not be
prepared to generate wakeup events.
3. The freeze_noirq phase is analogous to the suspend_noirq phase discussed
above, except again that the device should not be put in a low-power
state and should not be allowed to generate wakeup events.
At this point the system image is created. All devices should be inactive and
the contents of memory should remain undisturbed while this happens, so that the
image forms an atomic snapshot of the system state.
4. The thaw_noirq phase is analogous to the resume_noirq phase discussed
above. The main difference is that its methods can assume the device is
in the same state as at the end of the freeze_noirq phase.
5. The thaw phase is analogous to the resume phase discussed above. Its
methods should bring the device back to an operating state, so that it
can be used for saving the image if necessary.
6. The complete phase is discussed in the "Leaving System Suspend" section
above.
At this point the system image is saved, and the devices then need to be
prepared for the upcoming system shutdown. This is much like suspending them
before putting the system into the standby or memory sleep state, and the phases
are similar.
7. The prepare phase is discussed above.
8. The poweroff phase is analogous to the suspend phase.
9. The poweroff_noirq phase is analogous to the suspend_noirq phase.
The poweroff and poweroff_noirq callbacks should do essentially the same things
as the suspend and suspend_noirq callbacks. The only notable difference is that
they need not store the device register values, because the registers should
already have been stored during the freeze or freeze_noirq phases.
Leaving Hibernation
-------------------
Resuming from hibernation is, again, more complicated than resuming from a sleep
state in which the contents of main memory are preserved, because it requires
a system image to be loaded into memory and the pre-hibernation memory contents
to be restored before control can be passed back to the image kernel.
Although in principle, the image might be loaded into memory and the
pre-hibernation memory contents restored by the boot loader, in practice this
can't be done because boot loaders aren't smart enough and there is no
established protocol for passing the necessary information. So instead, the
boot loader loads a fresh instance of the kernel, called the boot kernel, into
memory and passes control to it in the usual way. Then the boot kernel reads
the system image, restores the pre-hibernation memory contents, and passes
control to the image kernel. Thus two different kernels are involved in
resuming from hibernation. In fact, the boot kernel may be completely different
from the image kernel: a different configuration and even a different version.
This has important consequences for device drivers and their subsystems.
To be able to load the system image into memory, the boot kernel needs to
include at least a subset of device drivers allowing it to access the storage
medium containing the image, although it doesn't need to include all of the
drivers present in the image kernel. After the image has been loaded, the
devices managed by the boot kernel need to be prepared for passing control back
to the image kernel. This is very similar to the initial steps involved in
creating a system image, and it is accomplished in the same way, using prepare,
freeze, and freeze_noirq phases. However the devices affected by these phases
are only those having drivers in the boot kernel; other devices will still be in
whatever state the boot loader left them.
Should the restoration of the pre-hibernation memory contents fail, the boot
kernel would go through the "thawing" procedure described above, using the
thaw_noirq, thaw, and complete phases, and then continue running normally. This
happens only rarely. Most often the pre-hibernation memory contents are
restored successfully and control is passed to the image kernel, which then
becomes responsible for bringing the system back to the working state.
To achieve this, the image kernel must restore the devices' pre-hibernation
functionality. The operation is much like waking up from the memory sleep
state, although it involves different phases:
restore_noirq, restore, complete
1. The restore_noirq phase is analogous to the resume_noirq phase.
2. The restore phase is analogous to the resume phase.
3. The complete phase is discussed above.
The main difference from resume[_noirq] is that restore[_noirq] must assume the
device has been accessed and reconfigured by the boot loader or the boot kernel.
Consequently the state of the device may be different from the state remembered
from the freeze and freeze_noirq phases. The device may even need to be reset
and completely re-initialized. In many cases this difference doesn't matter, so
the resume[_noirq] and restore[_norq] method pointers can be set to the same
routines. Nevertheless, different callback pointers are used in case there is a
situation where it actually matters.
System Devices
--------------
System devices (sysdevs) follow a slightly different API, which can be found in
include/linux/sysdev.h
drivers/base/sys.c
System devices will be suspended with interrupts disabled, and after all other
devices have been suspended. On resume, they will be resumed before any other
devices, and also with interrupts disabled. These things occur in special
"sysdev_driver" phases, which affect only system devices.
Thus, after the suspend_noirq (or freeze_noirq or poweroff_noirq) phase, when
the non-boot CPUs are all offline and IRQs are disabled on the remaining online
CPU, then a sysdev_driver.suspend phase is carried out, and the system enters a
sleep state (or a system image is created). During resume (or after the image
has been created or loaded) a sysdev_driver.resume phase is carried out, IRQs
are enabled on the only online CPU, the non-boot CPUs are enabled, and the
resume_noirq (or thaw_noirq or restore_noirq) phase begins.
Code to actually enter and exit the system-wide low power state sometimes
involves hardware details that are only known to the boot firmware, and
may leave a CPU running software (from SRAM or flash memory) that monitors
the system and manages its wakeup sequence.
Device Low Power (suspend) States
---------------------------------
Device low-power states aren't very standard. One device might only handle
Device low-power states aren't standard. One device might only handle
"on" and "off, while another might support a dozen different versions of
"on" (how many engines are active?), plus a state that gets back to "on"
faster than from a full "off".
@ -265,7 +546,7 @@ PCI device may not perform DMA or issue IRQs, and any wakeup events it
issues would be issued through the PME# bus signal. Plus, there are
several PCI-standard device states, some of which are optional.
In contrast, integrated system-on-chip processors often use irqs as the
In contrast, integrated system-on-chip processors often use IRQs as the
wakeup event sources (so drivers would call enable_irq_wake) and might
be able to treat DMA completion as a wakeup event (sometimes DMA can stay
active too, it'd only be the CPU and some peripherals that sleep).
@ -284,120 +565,17 @@ ways; the aforementioned LCD might be active in one product's "standby",
but a different product using the same SOC might work differently.
Meaning of pm_message_t.event
-----------------------------
Parameters to suspend calls include the device affected and a message of
type pm_message_t, which has one field: the event. If driver does not
recognize the event code, suspend calls may abort the request and return
a negative errno. However, most drivers will be fine if they implement
PM_EVENT_SUSPEND semantics for all messages.
Power Management Notifiers
--------------------------
There are some operations that cannot be carried out by the power management
callbacks discussed above, because the callbacks occur too late or too early.
To handle these cases, subsystems and device drivers may register power
management notifiers that are called before tasks are frozen and after they have
been thawed. Generally speaking, the PM notifiers are suitable for performing
actions that either require user space to be available, or at least won't
interfere with user space.
The event codes are used to refine the goal of suspending the device, and
mostly matter when creating or resuming system memory image snapshots, as
used with suspend-to-disk:
PM_EVENT_SUSPEND -- quiesce the driver and put hardware into a low-power
state. When used with system sleep states like "suspend-to-RAM" or
"standby", the upcoming resume() call will often be able to rely on
state kept in hardware, or issue system wakeup events.
PM_EVENT_HIBERNATE -- Put hardware into a low-power state and enable wakeup
events as appropriate. It is only used with hibernation
(suspend-to-disk) and few devices are able to wake up the system from
this state; most are completely powered off.
PM_EVENT_FREEZE -- quiesce the driver, but don't necessarily change into
any low power mode. A system snapshot is about to be taken, often
followed by a call to the driver's resume() method. Neither wakeup
events nor DMA are allowed.
PM_EVENT_PRETHAW -- quiesce the driver, knowing that the upcoming resume()
will restore a suspend-to-disk snapshot from a different kernel image.
Drivers that are smart enough to look at their hardware state during
resume() processing need that state to be correct ... a PRETHAW could
be used to invalidate that state (by resetting the device), like a
shutdown() invocation would before a kexec() or system halt. Other
drivers might handle this the same way as PM_EVENT_FREEZE. Neither
wakeup events nor DMA are allowed.
To enter "standby" (ACPI S1) or "Suspend to RAM" (STR, ACPI S3) states, or
the similarly named APM states, only PM_EVENT_SUSPEND is used; the other event
codes are used for hibernation ("Suspend to Disk", STD, ACPI S4).
There's also PM_EVENT_ON, a value which never appears as a suspend event
but is sometimes used to record the "not suspended" device state.
Resuming Devices
----------------
Resuming is done in multiple phases, much like suspending, with all
devices processing each phase's calls before the next phase begins.
The phases are seen by driver notifications issued in this order:
1 bus.resume(dev) reverses the effects of bus.suspend(). This may
be morphed into a device driver call with bus-specific parameters;
implementations may sleep.
2 class.resume(dev) is called for devices associated with a class
that has such a method. Implementations may sleep.
This reverses the effects of class.suspend(), and would usually
reactivate the device's I/O queue.
At the end of those phases, drivers should normally be as functional as
they were before suspending: I/O can be performed using DMA and IRQs, and
the relevant clocks are gated on. The device need not be "fully on"; it
might be in a runtime lowpower/suspend state that acts as if it were.
However, the details here may again be platform-specific. For example,
some systems support multiple "run" states, and the mode in effect at
the end of resume() might not be the one which preceded suspension.
That means availability of certain clocks or power supplies changed,
which could easily affect how a driver works.
Drivers need to be able to handle hardware which has been reset since the
suspend methods were called, for example by complete reinitialization.
This may be the hardest part, and the one most protected by NDA'd documents
and chip errata. It's simplest if the hardware state hasn't changed since
the suspend() was called, but that can't always be guaranteed.
Drivers must also be prepared to notice that the device has been removed
while the system was powered off, whenever that's physically possible.
PCMCIA, MMC, USB, Firewire, SCSI, and even IDE are common examples of busses
where common Linux platforms will see such removal. Details of how drivers
will notice and handle such removals are currently bus-specific, and often
involve a separate thread.
Note that the bus-specific runtime PM wakeup mechanism can exist, and might
be defined to share some of the same driver code as for system wakeup. For
example, a bus-specific device driver's resume() method might be used there,
so it wouldn't only be called from bus.resume() during system-wide wakeup.
See bus-specific information about how runtime wakeup events are handled.
System Devices
--------------
System devices follow a slightly different API, which can be found in
include/linux/sysdev.h
drivers/base/sys.c
System devices will only be suspended with interrupts disabled, and after
all other devices have been suspended. On resume, they will be resumed
before any other devices, and also with interrupts disabled.
That is, IRQs are disabled, the suspend_late() phase begins, then the
sysdev_driver.suspend() phase, and the system enters a sleep state. Then
the sysdev_driver.resume() phase begins, followed by the resume_early()
phase, after which IRQs are enabled.
Code to actually enter and exit the system-wide low power state sometimes
involves hardware details that are only known to the boot firmware, and
may leave a CPU running software (from SRAM or flash memory) that monitors
the system and manages its wakeup sequence.
For details refer to Documentation/power/notifiers.txt.
Runtime Power Management
@ -407,82 +585,23 @@ running. This feature is useful for devices that are not being used, and
can offer significant power savings on a running system. These devices
often support a range of runtime power states, which might use names such
as "off", "sleep", "idle", "active", and so on. Those states will in some
cases (like PCI) be partially constrained by a bus the device uses, and will
cases (like PCI) be partially constrained by the bus the device uses, and will
usually include hardware states that are also used in system sleep states.
However, note that if a driver puts a device into a runtime low power state
and the system then goes into a system-wide sleep state, it normally ought
to resume into that runtime low power state rather than "full on". Such
distinctions would be part of the driver-internal state machine for that
hardware; the whole point of runtime power management is to be sure that
drivers are decoupled in that way from the state machine governing phases
of the system-wide power/sleep state transitions.
A system-wide power transition can be started while some devices are in low
power states due to runtime power management. The system sleep PM callbacks
should recognize such situations and react to them appropriately, but the
necessary actions are subsystem-specific.
In some cases the decision may be made at the subsystem level while in other
cases the device driver may be left to decide. In some cases it may be
desirable to leave a suspended device in that state during a system-wide power
transition, but in other cases the device must be put back into the full-power
state temporarily, for example so that its system wakeup capability can be
disabled. This all depends on the hardware and the design of the subsystem and
device driver in question.
Power Saving Techniques
-----------------------
Normally runtime power management is handled by the drivers without specific
userspace or kernel intervention, by device-aware use of techniques like:
Using information provided by other system layers
- stay deeply "off" except between open() and close()
- if transceiver/PHY indicates "nobody connected", stay "off"
- application protocols may include power commands or hints
Using fewer CPU cycles
- using DMA instead of PIO
- removing timers, or making them lower frequency
- shortening "hot" code paths
- eliminating cache misses
- (sometimes) offloading work to device firmware
Reducing other resource costs
- gating off unused clocks in software (or hardware)
- switching off unused power supplies
- eliminating (or delaying/merging) IRQs
- tuning DMA to use word and/or burst modes
Using device-specific low power states
- using lower voltages
- avoiding needless DMA transfers
Read your hardware documentation carefully to see the opportunities that
may be available. If you can, measure the actual power usage and check
it against the budget established for your project.
Examples: USB hosts, system timer, system CPU
----------------------------------------------
USB host controllers make interesting, if complex, examples. In many cases
these have no work to do: no USB devices are connected, or all of them are
in the USB "suspend" state. Linux host controller drivers can then disable
periodic DMA transfers that would otherwise be a constant power drain on the
memory subsystem, and enter a suspend state. In power-aware controllers,
entering that suspend state may disable the clock used with USB signaling,
saving a certain amount of power.
The controller will be woken from that state (with an IRQ) by changes to the
signal state on the data lines of a given port, for example by an existing
peripheral requesting "remote wakeup" or by plugging a new peripheral. The
same wakeup mechanism usually works from "standby" sleep states, and on some
systems also from "suspend to RAM" (or even "suspend to disk") states.
(Except that ACPI may be involved instead of normal IRQs, on some hardware.)
System devices like timers and CPUs may have special roles in the platform
power management scheme. For example, system timers using a "dynamic tick"
approach don't just save CPU cycles (by eliminating needless timer IRQs),
but they may also open the door to using lower power CPU "idle" states that
cost more than a jiffie to enter and exit. On x86 systems these are states
like "C3"; note that periodic DMA transfers from a USB host controller will
also prevent entry to a C3 state, much like a periodic timer IRQ.
That kind of runtime mechanism interaction is common. "System On Chip" (SOC)
processors often have low power idle modes that can't be entered unless
certain medium-speed clocks (often 12 or 48 MHz) are gated off. When the
drivers gate those clocks effectively, then the system idle task may be able
to use the lower power idle modes and thereby increase battery life.
If the CPU can have a "cpufreq" driver, there also may be opportunities
to shift to lower voltage settings and reduce the power cost of executing
a given number of instructions. (Without voltage adjustment, it's rare
for cpufreq to save much power; the cost-per-instruction must go down.)
During system-wide resume from a sleep state it's best to put devices into the
full-power state, as explained in Documentation/power/runtime_pm.txt. Refer to
that document for more information regarding this particular issue as well as
for information on the device runtime power management framework in general.

48
Documentation/power/pm_qos_interface.txt
View File

@ -18,44 +18,46 @@ and pm_qos_params.h. This is done because having the available parameters
being runtime configurable or changeable from a driver was seen as too easy to
abuse.
For each parameter a list of performance requirements is maintained along with
For each parameter a list of performance requests is maintained along with
an aggregated target value. The aggregated target value is updated with
changes to the requirement list or elements of the list. Typically the
aggregated target value is simply the max or min of the requirement values held
changes to the request list or elements of the list. Typically the
aggregated target value is simply the max or min of the request values held
in the parameter list elements.
From kernel mode the use of this interface is simple:
pm_qos_add_requirement(param_id, name, target_value):
Will insert a named element in the list for that identified PM_QOS parameter
with the target value. Upon change to this list the new target is recomputed
and any registered notifiers are called only if the target value is now
different.
pm_qos_update_requirement(param_id, name, new_target_value):
Will search the list identified by the param_id for the named list element and
then update its target value, calling the notification tree if the aggregated
target is changed. with that name is already registered.
handle = pm_qos_add_request(param_class, target_value):
Will insert an element into the list for that identified PM_QOS class with the
target value. Upon change to this list the new target is recomputed and any
registered notifiers are called only if the target value is now different.
Clients of pm_qos need to save the returned handle.
pm_qos_remove_requirement(param_id, name):
Will search the identified list for the named element and remove it, after
removal it will update the aggregate target and call the notification tree if
the target was changed as a result of removing the named requirement.
void pm_qos_update_request(handle, new_target_value):
Will update the list element pointed to by the handle with the new target value
and recompute the new aggregated target, calling the notification tree if the
target is changed.
void pm_qos_remove_request(handle):
Will remove the element. After removal it will update the aggregate target and
call the notification tree if the target was changed as a result of removing
the request.
From user mode:
Only processes can register a pm_qos requirement. To provide for automatic
cleanup for process the interface requires the process to register its
parameter requirements in the following way:
Only processes can register a pm_qos request. To provide for automatic
cleanup of a process, the interface requires the process to register its
parameter requests in the following way:
To register the default pm_qos target for the specific parameter, the process
must open one of /dev/[cpu_dma_latency, network_latency, network_throughput]
As long as the device node is held open that process has a registered
requirement on the parameter. The name of the requirement is "process_<PID>"
derived from the current->pid from within the open system call.
request on the parameter.
To change the requested target value the process needs to write a s32 value to
the open device node. This translates to a pm_qos_update_requirement call.
To change the requested target value the process needs to write an s32 value to
the open device node. Alternatively the user mode program could write a hex
string for the value using 10 char long format e.g. "0x12345678". This
translates to a pm_qos_update_request call.
To remove the user mode request for a target value simply close the device
node.

10
Documentation/power/regulator/consumer.txt
View File

@ -8,11 +8,11 @@ Please see overview.txt for a description of the terms used in this text.
1. Consumer Regulator Access (static & dynamic drivers)
=======================================================
A consumer driver can get access to it's supply regulator by calling :-
A consumer driver can get access to its supply regulator by calling :-
regulator = regulator_get(dev, "Vcc");
The consumer passes in it's struct device pointer and power supply ID. The core
The consumer passes in its struct device pointer and power supply ID. The core
then finds the correct regulator by consulting a machine specific lookup table.
If the lookup is successful then this call will return a pointer to the struct
regulator that supplies this consumer.
@ -34,7 +34,7 @@ usually be called in your device drivers probe() and remove() respectively.
2. Regulator Output Enable & Disable (static & dynamic drivers)
====================================================================
A consumer can enable it's power supply by calling:-
A consumer can enable its power supply by calling:-
int regulator_enable(regulator);
@ -49,7 +49,7 @@ int regulator_is_enabled(regulator);
This will return > zero when the regulator is enabled.
A consumer can disable it's supply when no longer needed by calling :-
A consumer can disable its supply when no longer needed by calling :-
int regulator_disable(regulator);
@ -140,7 +140,7 @@ by calling :-
int regulator_set_optimum_mode(struct regulator *regulator, int load_uA);
This will cause the core to recalculate the total load on the regulator (based
on all it's consumers) and change operating mode (if necessary and permitted)
on all its consumers) and change operating mode (if necessary and permitted)
to best match the current operating load.
The load_uA value can be determined from the consumers datasheet. e.g.most

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