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authorOliver Hartkopp <oliver@hartkopp.net>2008-09-23 14:53:14 -0700
committerDavid S. Miller <davem@davemloft.net>2008-09-23 14:53:14 -0700
commite5d2304802a63304a54cff010209c4a717a2509f (patch)
tree978aaba0b03f6bf9564d7c55c6e9332d046060cb /Documentation/networking/can.txt
parent28e3487b7dd8a9791baac924bc887140ec747bed (diff)
can: Add documentation for virtual CAN driver usage
This patch adds a usage documentation for the virtual CAN driver (vcan). Signed-off-by: Oliver Hartkopp <oliver@hartkopp.net> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'Documentation/networking/can.txt')
-rw-r--r--Documentation/networking/can.txt44
1 files changed, 40 insertions, 4 deletions
diff --git a/Documentation/networking/can.txt b/Documentation/networking/can.txt
index 297ba7b1cca..2035bc4932f 100644
--- a/Documentation/networking/can.txt
+++ b/Documentation/networking/can.txt
@@ -35,8 +35,9 @@ This file contains
6.1 general settings
6.2 local loopback of sent frames
6.3 CAN controller hardware filters
- 6.4 currently supported CAN hardware
- 6.5 todo
+ 6.4 The virtual CAN driver (vcan)
+ 6.5 currently supported CAN hardware
+ 6.6 todo
7 Credits
@@ -584,7 +585,42 @@ solution for a couple of reasons:
@133MHz with four SJA1000 CAN controllers from 2002 under heavy bus
load without any problems ...
- 6.4 currently supported CAN hardware (September 2007)
+ 6.4 The virtual CAN driver (vcan)
+
+ Similar to the network loopback devices, vcan offers a virtual local
+ CAN interface. A full qualified address on CAN consists of
+
+ - a unique CAN Identifier (CAN ID)
+ - the CAN bus this CAN ID is transmitted on (e.g. can0)
+
+ so in common use cases more than one virtual CAN interface is needed.
+
+ The virtual CAN interfaces allow the transmission and reception of CAN
+ frames without real CAN controller hardware. Virtual CAN network
+ devices are usually named 'vcanX', like vcan0 vcan1 vcan2 ...
+ When compiled as a module the virtual CAN driver module is called vcan.ko
+
+ Since Linux Kernel version 2.6.24 the vcan driver supports the Kernel
+ netlink interface to create vcan network devices. The creation and
+ removal of vcan network devices can be managed with the ip(8) tool:
+
+ - Create a virtual CAN network interface:
+ ip link add type vcan
+
+ - Create a virtual CAN network interface with a specific name 'vcan42':
+ ip link add dev vcan42 type vcan
+
+ - Remove a (virtual CAN) network interface 'vcan42':
+ ip link del vcan42
+
+ The tool 'vcan' from the SocketCAN SVN repository on BerliOS is obsolete.
+
+ Virtual CAN network device creation in older Kernels:
+ In Linux Kernel versions < 2.6.24 the vcan driver creates 4 vcan
+ netdevices at module load time by default. This value can be changed
+ with the module parameter 'numdev'. E.g. 'modprobe vcan numdev=8'
+
+ 6.5 currently supported CAN hardware
On the project website http://developer.berlios.de/projects/socketcan
there are different drivers available:
@@ -603,7 +639,7 @@ solution for a couple of reasons:
Please check the Mailing Lists on the berlios OSS project website.
- 6.5 todo (September 2007)
+ 6.6 todo
The configuration interface for CAN network drivers is still an open
issue that has not been finalized in the socketcan project. Also the