staging: mei: updating mei driver documentation
The following changes were made in the document: 1. Update URLs to working links 2. remove old information about module parameters 3. Add IOCTL information. 4. cleanups and fix spelling 5. driver changed from character device to misc character device Signed-off-by: Oren Weil <oren.jer.weil@intel.com> Signed-off-by: Tomas Winkler <tomas.winkler@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Oren Weil
Greg Kroah-Hartman
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Intel MEI
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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
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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 (Intel ME) is an isolated andprotected 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
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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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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
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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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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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[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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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 host processor has crashed or is in a sleep state.
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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 maintenance)
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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 on
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policies set by a remote management console
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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/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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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/WordDocuments/aboutintelamt.htm
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http://software.intel.com/sites/manageability/AMT_Implementation_and_Reference_Guide
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MEI Driver
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Intel MEI Driver
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=======================
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The driver exposes a character device called /dev/mei.
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The driver exposes a misc 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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An application maintains communication with an Intel ME feature while
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/dev/mei is open. The binding to a specific features 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 (AMTHI) feature requires multiple
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simultaneous user applications, therefore the MEI driver handles
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The Intel AMT Host Interface (Intel AMTHI) feature supports multiple
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simultaneous user applications. Therefore, the Intel 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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The driver is oblivious to data that is passed between firmware feature
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and host application.
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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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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 application communicating with AMTHI client:
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A code snippet for an application communicating with
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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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@ -80,7 +76,7 @@ A Code snippet for application communicating with AMTHI client:
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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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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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@ -95,76 +91,106 @@ A Code snippet for application communicating with AMTHI client:
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[...]
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close(fd);
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ME Applications:
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IOCTL:
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======
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The Intel MEI Driver supports the following IOCTL command:
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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 upto 2k bytes).
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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
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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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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_
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Reference_Guide/WordDocuments/localaccess1.htm
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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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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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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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2) Intel AMT Remote configuration using a Local Agent:
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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.
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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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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/WordDocuments/remoteconfigurationwithalocalagent.htm
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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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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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to any subsciber to this event. This mechanism means that
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IT knows when a platform crashes even when there is a hard failureon 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) MEI driver – connects to the watchdog (WD) feature,
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configures the watchdog and sends the heartbeats.
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2) Intel MEI driver - connects to the watchdog feature, configures the
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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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The Intel MEI driver uses the kernel watchdog to configure the Intel AMT
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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 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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If the Intel AMT Watchdog feature does not exist (i.e. the connection failed),
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the Intel MEI driver will disable the sending of heartbeats.
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Supported Chipsets:
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==================
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