267 lines
9.2 KiB
Plaintext
267 lines
9.2 KiB
Plaintext
Intel(R) Management Engine Interface (Intel(R) 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 protected computing
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resource (Co-processor) residing inside certain Intel chipsets. The Intel ME
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provides support for computer/IT management features. The feature set
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depends on the Intel chipset SKU.
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The Intel Management Engine Interface (Intel MEI, previously known as HECI)
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is the interface between the Host and Intel ME. This interface is exposed
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to the host as a PCI device. The Intel MEI Driver is in charge of the
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communication channel between a host application and the Intel ME feature.
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Each Intel ME feature (Intel ME Client) is addressed by a GUID/UUID and
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each client has its own protocol. The protocol is message-based with a
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header and payload up to 512 bytes.
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Prominent usage of the Intel ME Interface is to communicate with Intel(R)
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Active Management Technology (Intel AMT) implemented in firmware running on
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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 operating system running on the host processor has crashed or
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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
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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
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on 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/S or WS-Management protocol over
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HTTP/S that are received from a remote 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
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Intel MEI Driver
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================
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The driver exposes a misc device called /dev/mei.
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An application maintains communication with an Intel ME feature while
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/dev/mei is open. The binding to a specific feature is performed by calling
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MEI_CONNECT_CLIENT_IOCTL, which passes the desired UUID.
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The number of instances of an Intel ME feature that can be opened
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at the same time depends on the Intel 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 (Intel AMTHI) feature supports multiple
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simultaneous user connected applications. The Intel MEI driver
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handles this internally by maintaining request queues for the applications.
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The driver is transparent to data that are passed between firmware feature
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and host application.
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Because some of the Intel ME features can change the system
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configuration, the driver by default allows only a privileged
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user to access it.
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A code snippet for an application communicating with Intel 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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IOCTL
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=====
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The Intel MEI Driver supports the following IOCTL commands:
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IOCTL_MEI_CONNECT_CLIENT Connect to firmware Feature (client).
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usage:
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struct mei_connect_client_data clientData;
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ioctl(fd, IOCTL_MEI_CONNECT_CLIENT, &clientData);
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inputs:
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mei_connect_client_data struct contain the following
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input field:
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in_client_uuid - UUID of the FW Feature that needs
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to connect to.
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outputs:
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out_client_properties - Client Properties: MTU and Protocol Version.
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error returns:
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EINVAL Wrong IOCTL Number
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ENODEV Device or Connection is not initialized or ready.
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(e.g. Wrong UUID)
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ENOMEM Unable to allocate memory to client internal data.
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EFAULT Fatal Error (e.g. Unable to access user input data)
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EBUSY Connection Already Open
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Notes:
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max_msg_length (MTU) in client properties describes the maximum
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data that can be sent or received. (e.g. if MTU=2K, can send
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requests up to bytes 2k and received responses up to 2k bytes).
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IOCTL_MEI_NOTIFY_SET: enable or disable event notifications
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Usage:
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uint32_t enable;
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ioctl(fd, IOCTL_MEI_NOTIFY_SET, &enable);
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Inputs:
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uint32_t enable = 1;
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or
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uint32_t enable[disable] = 0;
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Error returns:
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EINVAL Wrong IOCTL Number
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ENODEV Device is not initialized or the client not connected
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ENOMEM Unable to allocate memory to client internal data.
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EFAULT Fatal Error (e.g. Unable to access user input data)
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EOPNOTSUPP if the device doesn't support the feature
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Notes:
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The client must be connected in order to enable notification events
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IOCTL_MEI_NOTIFY_GET : retrieve event
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Usage:
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uint32_t event;
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ioctl(fd, IOCTL_MEI_NOTIFY_GET, &event);
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Outputs:
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1 - if an event is pending
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0 - if there is no even pending
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Error returns:
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EINVAL Wrong IOCTL Number
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ENODEV Device is not initialized or the client not connected
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ENOMEM Unable to allocate memory to client internal data.
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EFAULT Fatal Error (e.g. Unable to access user input data)
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EOPNOTSUPP if the device doesn't support the feature
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Notes:
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The client must be connected and event notification has to be enabled
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in order to receive an event
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Intel 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 Intel AMT Release
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2.0 and later releases in the same way that network applications do via SOAP
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over HTTP (deprecated starting with Release 6.0) or with WS-Management over
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SOAP over HTTP. This means that some Intel AMT features can be accessed from a
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local application using the same network interface as a remote application
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communicating with Intel AMT over the network.
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When a local application sends a message addressed to the local Intel AMT host
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name, the Intel LMS, which listens for traffic directed to the host name,
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intercepts the message and routes it to the Intel MEI.
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For more information:
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http://software.intel.com/sites/manageability/AMT_Implementation_and_Reference_Guide
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Under "About Intel AMT" => "Local Access"
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For downloading Intel LMS:
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http://software.intel.com/en-us/articles/download-the-latest-intel-amt-open-source-drivers/
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The Intel LMS opens a connection using the Intel MEI driver to the Intel LMS
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firmware feature using a defined UUID and then communicates with the feature
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using a protocol called Intel AMT Port Forwarding Protocol (Intel APF protocol).
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The protocol is used to maintain multiple sessions with Intel AMT from a
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single application.
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See the protocol specification in the Intel AMT Software Development Kit (SDK)
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http://software.intel.com/sites/manageability/AMT_Implementation_and_Reference_Guide
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Under "SDK Resources" => "Intel(R) vPro(TM) Gateway (MPS)"
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=> "Information for Intel(R) vPro(TM) Gateway Developers"
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=> "Description of the Intel AMT Port Forwarding (APF) Protocol"
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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. The remote
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configuration process may involve an ISV-developed remote configuration
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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
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Under "Setup and Configuration of Intel AMT" =>
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"SDK Tools Supporting Setup and Configuration" =>
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"Using the Local Agent Sample"
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An open source Intel AMT configuration utility, implementing a local agent
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that accesses the Intel MEI driver, can be found here:
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http://software.intel.com/en-us/articles/download-the-latest-intel-amt-open-source-drivers/
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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 any subscriber to this event. This mechanism means that
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IT knows when a platform crashes even when there is a hard failure on the host.
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The Intel AMT Watchdog is composed of two parts:
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1) Firmware feature - receives the heartbeats
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and sends an event when the heartbeats stop.
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2) Intel MEI iAMT watchdog driver - connects to the watchdog feature,
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configures the watchdog and sends the heartbeats.
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The Intel iAMT watchdog MEI driver uses the kernel watchdog API to configure
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the Intel AMT Watchdog and to send heartbeats to it. The default timeout of the
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watchdog is 120 seconds.
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If the Intel AMT is not enabled in the firmware then the watchdog client won't enumerate
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on the me client bus and watchdog devices won't be exposed.
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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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