Intel(R) Management Engine Interface (Intel(R) MEI) =================================================== Introduction ============ 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 maintenance) - 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: http://software.intel.com/sites/manageability/AMT_Implementation_and_Reference_Guide 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 feature 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 connected applications. The Intel MEI driver handles this internally by maintaining request queues for the applications. The driver is transparent to data that are 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); printf("Ver=%d, MaxLen=%ld\n", data.d.in_client_uuid.protocol_version, data.d.in_client_uuid.max_msg_length); [...] write(fd, amthi_req_data, amthi_req_data_len); [...] read(fd, &amthi_res_data, amthi_res_data_len); [...] close(fd); IOCTL ===== The Intel MEI Driver supports the following IOCTL command: IOCTL_MEI_CONNECT_CLIENT Connect to firmware Feature (client). usage: struct mei_connect_client_data clientData; ioctl(fd, IOCTL_MEI_CONNECT_CLIENT, &clientData); inputs: mei_connect_client_data struct contain the following input field: in_client_uuid - UUID of the FW Feature that needs to connect to. outputs: out_client_properties - Client Properties: MTU and Protocol Version. error returns: 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 Notes: 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 up to 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: http://software.intel.com/sites/manageability/AMT_Implementation_and_Reference_Guide Under "About Intel AMT" => "Local Access" For downloading Intel LMS: http://software.intel.com/en-us/articles/download-the-latest-intel-amt-open-source-drivers/ 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 single application. See the protocol specification in the Intel AMT Software Development Kit (SDK) http://software.intel.com/sites/manageability/AMT_Implementation_and_Reference_Guide 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: http://software.intel.com/sites/manageability/AMT_Implementation_and_Reference_Guide 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: http://software.intel.com/en-us/articles/download-the-latest-intel-amt-open-source-drivers/ 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 API 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. Supported Chipsets ================== 7 Series Chipset Family 6 Series Chipset Family 5 Series Chipset Family 4 Series Chipset Family Mobile 4 Series Chipset Family ICH9 82946GZ/GL 82G35 Express 82Q963/Q965 82P965/G965 Mobile PM965/GM965 Mobile GME965/GLE960 82Q35 Express 82G33/G31/P35/P31 Express 82Q33 Express 82X38/X48 Express --- linux-mei@linux.intel.com