staging/mei: MEI Driver documentations
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com> Signed-off-by: Oren Weil <oren.jer.weil@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Greg Kroah-Hartman
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drivers/staging/mei/mei.txt
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drivers/staging/mei/mei.txt
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Intel MEI
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=======================
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Introduction
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=======================
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The Intel Management Engine (Intel ME) is an isolated and
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protected computing resource (Coprocessor) residing inside
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Intel chipsets. The Intel ME provides support for computer/IT
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management features.
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The Feature set depends on the Intel chipset SKU.
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The Intel Management Engine Interface (Intel MEI, previously known
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as HECI) is the interface between the Host and Intel ME.
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This interface is exposed to the host as a PCI device.
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The Intel MEI Driver is in charge of the communication channel
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between a host application and the ME feature.
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Each Intel ME feature (Intel ME Client) is addressed by
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GUID/UUID and each feature defines its own protocol.
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The protocol is message-based with a header and payload up to
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512 bytes.
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[place holder to URL to protocol definitions]
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Prominent usage of the Interface is to communicate with
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Intel Active Management Technology (Intel AMT)
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implemented in firmware running on the Intel ME.
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Intel AMT provides the ability to manage a host remotely out-of-band (OOB)
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even when the host processor has crashed or is in a sleep state.
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Some examples of Intel AMT usage are:
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- Monitoring hardware state and platform components
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- Remote power off/on (useful for green computing or overnight IT maintenance)
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- OS updates
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- Storage of useful platform information such as software assets
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- built-in hardware KVM
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- selective network isolation of Ethernet and IP protocol flows based on
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policies set by a remote management console
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- IDE device redirection from remote management console
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Intel AMT (OOB) communication is based on SOAP (deprecated
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starting with Release 6.0) over HTTP/HTTPS or WS-Management protocol
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over HTTP and HTTPS that are received from a remote
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management console application.
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For more information about Intel AMT:
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http://software.intel.com/sites/manageability/AMT_Implementation_and_Reference_Guide/WordDocuments/aboutintelamt.htm
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MEI Driver
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=======================
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The driver exposes a character device called /dev/mei.
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An application maintains communication with an ME feature while
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/dev/mei is open. The binding to a specific features is performed
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by calling MEI_CONNECT_CLIENT_IOCTL, which passes the desired UUID.
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The number of instances of an ME feature that can be opened
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at the same time depends on the ME feature, but most of the
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features allow only a single instance.
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The Intel AMT Host Interface (AMTHI) feature requires multiple
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simultaneous user applications, therefore the MEI driver handles
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this internally by maintaining request queues for the applications.
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The driver is oblivious to data that are passed between
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Because some of the ME features can change the system
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configuration, the driver by default allows only privileged
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user to access it.
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A Code snippet for application communicating with AMTHI client:
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struct mei_connect_client_data data;
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fd = open(MEI_DEVICE);
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data.d.in_client_uuid = AMTHI_UUID;
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ioctl(fd, IOCTL_MEI_CONNECT_CLIENT, &data);
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printf(“Ver=%d, MaxLen=%ld\n”,
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data.d.in_client_uuid.protocol_version,
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data.d.in_client_uuid.max_msg_length);
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[...]
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write(fd, amthi_req_data, amthi_req_data_len);
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[...]
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read(fd, &amthi_res_data, amthi_res_data_len);
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[...]
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close(fd);
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ME Applications:
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==============
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1) Intel Local Management Service (Intel LMS)
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Applications running locally on the platform communicate with
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Intel AMT Release 2.0 and later releases in the same way
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that network applications do via SOAP over HTTP (deprecated
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starting with Release 6.0) or with WS-Management over SOAP over
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HTTP. which means that some Intel AMT feature can be access
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from a local application using same Network interface as for
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remote application.
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When a local application sends a message addressed to the local
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Intel AMT host name, the Local Manageability Service (LMS),
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which listens for traffic directed to the host name, intercepts
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the message and routes it to the Intel Management Engine Interface.
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For more information:
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http://software.intel.com/sites/manageability/AMT_Implementation_and_
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Reference_Guide/WordDocuments/localaccess1.htm
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The LMS opens a connection using the MEI driver to the LMS
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FW feature using a defined UUID and then communicates with the
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feature using a protocol
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called Intel(R) AMT Port Forwarding Protocol (APF protocol).
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The protocol is used to maintain multiple sessions with
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Intel AMT from a single application.
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See the protocol specification in
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the Intel(R) AMT Implementation and Reference Guide
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http://software.intel.com/sites/manageability/AMT_Implementation_and_Reference_Guide/HTMLDocuments/MPSDocuments/Intel%20AMT%20Port%20Forwarding%20Protocol%20Reference%20Manual.pdf
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2) Intel AMT Remote configuration using a Local Agent:
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A Local Agent enables IT personnel to configure Intel AMT out-of-the-box
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without requiring installing additional data to enable setup.
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The remote configuration process may involve an ISV-developed remote
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configuration agent that runs on the host.
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For more information:
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http://software.intel.com/sites/manageability/AMT_Implementation_and_Reference_Guide/WordDocuments/remoteconfigurationwithalocalagent.htm
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How the Local Agent Works (including Command structs):
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http://software.intel.com/sites/manageability/AMT_Implementation_and_Reference_Guide/WordDocuments/howthelocalagentsampleworks.htm
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Intel AMT OS Health Watchdog:
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=============================
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The Intel AMT Watchdog is an OS Health (Hang/Crash) watchdog.
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Whenever the OS hangs or crashes, Intel AMT will send an event
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to whoever subscribed to this event. This mechanism means that
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IT knows when a platform crashes even when there is a hard failure
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on the host.
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The AMT Watchdog is composed of two parts:
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1) FW Feature - that receives the heartbeats
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and sends an event when the heartbeats stop.
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2) MEI driver – connects to the watchdog (WD) feature,
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configures the watchdog and sends the heartbeats.
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The MEI driver configures the Watchdog to expire by default
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every 120sec unless set by the user using module parameters.
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The Driver then sends heartbeats every 2sec.
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If WD feature does not exist (i.e. the connection failed),
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the MEI driver will disable the sending of heartbeats.
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Module Parameters
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=================
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watchdog_timeout - the user can use this module parameter
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to change the watchdog timeout setting.
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This value sets the Intel AMT watchdog timeout interval in seconds;
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the default value is 120sec.
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in order to disable the watchdog activites set the value to 0.
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Normal values should be between 120 and 65535
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Supported Chipsets:
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==================
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7 Series Chipset Family
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6 Series Chipset Family
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5 Series Chipset Family
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4 Series Chipset Family
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Mobile 4 Series Chipset Family
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ICH9
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82946GZ/GL
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82G35 Express
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82Q963/Q965
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82P965/G965
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Mobile PM965/GM965
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Mobile GME965/GLE960
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82Q35 Express
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82G33/G31/P35/P31 Express
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82Q33 Express
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82X38/X48 Express
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---
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linux-mei@linux.intel.com
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