Intel(R) Management Engine Interface (Intel(R) MEI)
The Intel Management Engine (Intel ME) is an isolated and protected computing
resource (Co-processor) residing inside certain Intel chipsets. The Intel ME
provides support for computer/IT management features. The feature set
depends on the Intel chipset SKU.
The Intel Management Engine Interface (Intel MEI, previously known as HECI)
is the interface between the Host and Intel ME. This interface is exposed
to the host as a PCI device. The Intel MEI Driver is in charge of the
communication channel between a host application and the Intel ME feature.
Each Intel ME feature (Intel ME Client) is addressed by a GUID/UUID and
each client has its own protocol. The protocol is message-based with a
header and payload up to 512 bytes.
Prominent usage of the Intel ME Interface is to communicate with Intel(R)
Active Management Technology (Intel AMT)implemented in firmware running on
the Intel ME.
Intel AMT provides the ability to manage a host remotely out-of-band (OOB)
even when the operating system running on the host processor has crashed or
is in a sleep state.
Some examples of Intel AMT usage are:
- Monitoring hardware state and platform components
- Remote power off/on (useful for green computing or overnight IT
- OS updates
- Storage of useful platform information such as software assets
- Built-in hardware KVM
- Selective network isolation of Ethernet and IP protocol flows based
on policies set by a remote management console
- IDE device redirection from remote management console
Intel AMT (OOB) communication is based on SOAP (deprecated
starting with Release 6.0) over HTTP/S or WS-Management protocol over
HTTP/S that are received from a remote management console application.
For more information about Intel AMT:
Intel MEI Driver
The driver exposes a misc device called /dev/mei.
An application maintains communication with an Intel ME feature while
/dev/mei is open. The binding to a specific features is performed by calling
MEI_CONNECT_CLIENT_IOCTL, which passes the desired UUID.
The number of instances of an Intel ME feature that can be opened
at the same time depends on the Intel ME feature, but most of the
features allow only a single instance.
The Intel AMT Host Interface (Intel AMTHI) feature supports multiple
simultaneous user applications. Therefore, the Intel MEI driver handles
this internally by maintaining request queues for the applications.
The driver is oblivious to data that is passed between firmware feature
and host application.
Because some of the Intel ME features can change the system
configuration, the driver by default allows only a privileged
user to access it.
A code snippet for an application communicating with
Intel AMTHI client:
struct mei_connect_client_data data;
fd = open(MEI_DEVICE);
data.d.in_client_uuid = AMTHI_UUID;
ioctl(fd, IOCTL_MEI_CONNECT_CLIENT, &data);
write(fd, amthi_req_data, amthi_req_data_len);
read(fd, &amthi_res_data, amthi_res_data_len);
The Intel MEI Driver supports the following IOCTL command:
IOCTL_MEI_CONNECT_CLIENT Connect to firmware Feature (client).
struct mei_connect_client_data clientData;
ioctl(fd, IOCTL_MEI_CONNECT_CLIENT, &clientData);
mei_connect_client_data struct contain the following
in_client_uuid - UUID of the FW Feature that needs
to connect to.
out_client_properties - Client Properties: MTU and Protocol Version.
EINVAL Wrong IOCTL Number
ENODEV Device or Connection is not initialized or ready.
(e.g. Wrong UUID)
ENOMEM Unable to allocate memory to client internal data.
EFAULT Fatal Error (e.g. Unable to access user input data)
EBUSY Connection Already Open
max_msg_length (MTU) in client properties describes the maximum
data that can be sent or received. (e.g. if MTU=2K, can send
requests up to bytes 2k and received responses upto 2k bytes).
Intel ME Applications:
1) Intel Local Management Service (Intel LMS)
Applications running locally on the platform communicate with Intel AMT Release
2.0 and later releases in the same way that network applications do via SOAP
over HTTP (deprecated starting with Release 6.0) or with WS-Management over
SOAP over HTTP. This means that some Intel AMT features can be accessed from a
local application using the same network interface as a remote application
communicating with Intel AMT over the network.
When a local application sends a message addressed to the local Intel AMT host
name, the Intel LMS, which listens for traffic directed to the host name,
intercepts the message and routes it to the Intel MEI.
For more information:
Under "About Intel AMT" => "Local Access"
For downloading Intel LMS:
The Intel LMS opens a connection using the Intel MEI driver to the Intel LMS
firmware feature using a defined UUID and then communicates with the feature
using a protocol called Intel AMT Port Forwarding Protocol(Intel APF protocol).
The protocol is used to maintain multiple sessions with Intel AMT from a
See the protocol specification in the Intel AMT Software Development Kit(SDK)
Under "SDK Resources" => "Intel(R) vPro(TM) Gateway(MPS)"
=> "Information for Intel(R) vPro(TM) Gateway Developers"
=> "Description of the Intel AMT Port Forwarding (APF)Protocol"
2) Intel AMT Remote configuration using a Local Agent
A Local Agent enables IT personnel to configure Intel AMT out-of-the-box
without requiring installing additional data to enable setup. The remote
configuration process may involve an ISV-developed remote configuration
agent that runs on the host.
For more information:
Under "Setup and Configuration of Intel AMT" =>
"SDK Tools Supporting Setup and Configuration" =>
"Using the Local Agent Sample"
An open source Intel AMT configuration utility, implementing a local agent
that accesses the Intel MEI driver, can be found here:
Intel AMT OS Health Watchdog:
The Intel AMT Watchdog is an OS Health (Hang/Crash) watchdog.
Whenever the OS hangs or crashes, Intel AMT will send an event
to any subscriber to this event. This mechanism means that
IT knows when a platform crashes even when there is a hard failure on the host.
The Intel AMT Watchdog is composed of two parts:
1) Firmware feature - receives the heartbeats
and sends an event when the heartbeats stop.
2) Intel MEI driver - connects to the watchdog feature, configures the
watchdog and sends the heartbeats.
The Intel MEI driver uses the kernel watchdog to configure the Intel AMT
Watchdog and to send heartbeats to it. The default timeout of the
watchdog is 120 seconds.
If the Intel AMT Watchdog feature does not exist (i.e. the connection failed),
the Intel MEI driver will disable the sending of heartbeats.
7 Series Chipset Family
6 Series Chipset Family
5 Series Chipset Family
4 Series Chipset Family
Mobile 4 Series Chipset Family