Host Embedded Controller Interface
Encyclopedia
Host Embedded Controller Interface, abbreviated as HECI, is a recent (introduced in 2006) technology used for Active Management Technology (AMT
) in Intel chipset
s that support Core 2 Duo microprocessor
s.
, variable data-rate
bus enables the Host and ME to communicate system management information and events in a standards-compliant way, essentially replacing the System Management Bus
(SMBus). The bus consists of four wires: a request and grant pair along with a serial transmit and receive data pair.
Original equipment manufacturers (OEM
s) have historically provided active management technologies through the use of proprietary
on-board controllers, such as Baseboard Management Controllers. These solutions typically suffer two main disadvantages due to their proprietary nature. High BOM
costs are usually incurred due to need for additional components and routing. High PLC costs are incurred due to the non-standard implementation, which increases software and hardware design and validation costs while remaining relatively inflexible to future changes. On the other hand, the inflexibility is even greater with HECI due to coupling HECI with a chipset, and having to redevelop HECI software for each different chipset as opposed to one common BMC software for multiple chipsets.
HECI and the previously used SMBus have the following aspects in common: the Host OS is able to control system management devices such as: on-board fan controllers, remote wake devices such as Wake-on-LAN
, power supply devices such as Smart Battery Data. Builtin HECI functionality and 3rd-party management cards can allow the Host OS to directly initiate management events (such as remote wake, or, out-of-band throttling to decrease thermal and power profile) in case HECI is supported by the running OS. Example devices are network card
s and graphics cards
. Besides that, both HECI and other ME technologies are chipset/ME vendor-specific.
s to enable support on a network card. With the HECI bus, the host is able to assert its request line (REQ#), the ME will assert its grant line (GNT#), and the host can send its message using its serial
transmit signal. Upon receipt of the Wake-on-LAN enable message on HECI, the ME directly enables Wake-on-LAN in the integrated (or externally supported) network device. Without HECI drivers in the OS, Wake-on-LAN functionality is lost even if standard network drivers would be able to enable it. This is a major problem in large-scale enterprise deployments with standard software images.
When the magic wake packet is received by the LAN device, the encapsulated data is passed to the ME, which has its own TCP/IP stack and can decapsulate the packet. The ME then asserts its request line (REQ#), the host acknowledges by asserting grant (GNT#), and the message is passed to the host to initiate a wake event.
With this technology, the magic packet may be encapsulated in TCP
packets thus allowing the packet to traverse network infrastructures via routers and thereby increasing the attack surface, something which traditional Wake-on-LAN does not enable. An advantage in Intel-centric deployments is that the solution does not require non-Intel drivers. If no host/ME interaction is needed, HECI and other ME technologies are OS
independent.
Intel Active Management Technology
Intel Active Management Technology is hardware-based technology for remotely managing and securing PCs out-of-band.Currently, Intel AMT is available in desktop PCs with Intel Core 2 processor with Intel vPro technology and available in laptop PCs with Centrino or Centrino 2 platform with vPro...
) in Intel chipset
Chipset
A chipset, PC chipset, or chip set refers to a group of integrated circuits, or chips, that are designed to work together. They are usually marketed as a single product.- Computers :...
s that support Core 2 Duo microprocessor
Microprocessor
A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...
s.
Details
The HECI bus allows the Host OS to communicate directly with the Manageability Engine (ME) integrated in the chipset. This bi-directionalBi-directional
Bi-directional may refer to:* Bi-directional text* Two-way communication* Bi-directional railway signalling* Controls at each end of a tram or railcar...
, variable data-rate
Bit rate
In telecommunications and computing, bit rate is the number of bits that are conveyed or processed per unit of time....
bus enables the Host and ME to communicate system management information and events in a standards-compliant way, essentially replacing the System Management Bus
System Management Bus
The System Management Bus is a single-ended simple two-wire bus for the purpose of lightweight communication...
(SMBus). The bus consists of four wires: a request and grant pair along with a serial transmit and receive data pair.
Original equipment manufacturers (OEM
Original Equipment Manufacturer
An original equipment manufacturer, or OEM, manufactures products or components that are purchased by a company and retailed under that purchasing company's brand name. OEM refers to the company that originally manufactured the product. When referring to automotive parts, OEM designates a...
s) have historically provided active management technologies through the use of proprietary
Proprietary hardware
Proprietary hardware is computer hardware which is owned by the proprietor.Historically, most early computer hardware was designed as proprietary until the 1980s, when IBM PC changed this paradigm...
on-board controllers, such as Baseboard Management Controllers. These solutions typically suffer two main disadvantages due to their proprietary nature. High BOM
Bill of materials
A bill of materials is a list of the raw materials, sub-assemblies, intermediate assemblies, sub-components, components, parts and the quantities of each needed to manufacture an end product...
costs are usually incurred due to need for additional components and routing. High PLC costs are incurred due to the non-standard implementation, which increases software and hardware design and validation costs while remaining relatively inflexible to future changes. On the other hand, the inflexibility is even greater with HECI due to coupling HECI with a chipset, and having to redevelop HECI software for each different chipset as opposed to one common BMC software for multiple chipsets.
HECI and the previously used SMBus have the following aspects in common: the Host OS is able to control system management devices such as: on-board fan controllers, remote wake devices such as Wake-on-LAN
Wake-on-LAN
Wake-on-LAN is an Ethernet computer networking standard that allows a computer to be turned on or woken up by a network message....
, power supply devices such as Smart Battery Data. Builtin HECI functionality and 3rd-party management cards can allow the Host OS to directly initiate management events (such as remote wake, or, out-of-band throttling to decrease thermal and power profile) in case HECI is supported by the running OS. Example devices are network card
Network card
A network interface controller is a computer hardware component that connects a computer to a computer network....
s and graphics cards
Video card
A video card, Graphics Card, or Graphics adapter is an expansion card which generates output images to a display. Most video cards offer various functions such as accelerated rendering of 3D scenes and 2D graphics, MPEG-2/MPEG-4 decoding, TV output, or the ability to connect multiple monitors...
. Besides that, both HECI and other ME technologies are chipset/ME vendor-specific.
Host Initiated Messages
- Read battery status
- Read thermal data
- Enable/disable wake devices
- Notify devices to change power state (thermal, performance, or power throttling)
Manageability Engine Initiated Messages
- Alert Host to battery event
- Low or Critical battery level
- Switch between A/C (wall) and D/C (battery)
- Alert Host to thermal event (Hot or Critical thermal trip)
- Change Fan Speed
- Detect network wake
- Boot/Shutdown System
- Detected Host Intrusion
- Change boot device
- Report system inventory
Example
As an example, assume the case of Wake-on-LAN. Traditionally, the OS controls Wake-on-LAN and must call third-party device driverDevice driver
In computing, a device driver or software driver is a computer program allowing higher-level computer programs to interact with a hardware device....
s to enable support on a network card. With the HECI bus, the host is able to assert its request line (REQ#), the ME will assert its grant line (GNT#), and the host can send its message using its serial
Serial communications
In telecommunication and computer science, serial communication is the process of sending data one bit at a time, sequentially, over a communication channel or computer bus. This is in contrast to parallel communication, where several bits are sent as a whole, on a link with several parallel channels...
transmit signal. Upon receipt of the Wake-on-LAN enable message on HECI, the ME directly enables Wake-on-LAN in the integrated (or externally supported) network device. Without HECI drivers in the OS, Wake-on-LAN functionality is lost even if standard network drivers would be able to enable it. This is a major problem in large-scale enterprise deployments with standard software images.
When the magic wake packet is received by the LAN device, the encapsulated data is passed to the ME, which has its own TCP/IP stack and can decapsulate the packet. The ME then asserts its request line (REQ#), the host acknowledges by asserting grant (GNT#), and the message is passed to the host to initiate a wake event.
With this technology, the magic packet may be encapsulated in TCP
Transmission Control Protocol
The Transmission Control Protocol is one of the core protocols of the Internet Protocol Suite. TCP is one of the two original components of the suite, complementing the Internet Protocol , and therefore the entire suite is commonly referred to as TCP/IP...
packets thus allowing the packet to traverse network infrastructures via routers and thereby increasing the attack surface, something which traditional Wake-on-LAN does not enable. An advantage in Intel-centric deployments is that the solution does not require non-Intel drivers. If no host/ME interaction is needed, HECI and other ME technologies are OS
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
independent.
See also
- Intel Active Management TechnologyIntel Active Management TechnologyIntel Active Management Technology is hardware-based technology for remotely managing and securing PCs out-of-band.Currently, Intel AMT is available in desktop PCs with Intel Core 2 processor with Intel vPro technology and available in laptop PCs with Centrino or Centrino 2 platform with vPro...
(AMT) - Baseboard management controller (BMC)
- System Management BusSystem Management BusThe System Management Bus is a single-ended simple two-wire bus for the purpose of lightweight communication...
(SMBus)