From: Havard Skinnemoen <hskinnem...@google.com> The IPMI document is expanded with a proposal to emulate BMC-side IPMI devices. This allows a QEMU instance running server software to interact with a different QEMU instance running BMC firmware, which should closely model how a real server system works.
Signed-off-by: Havard Skinnemoen <hskinnem...@google.com> Signed-off-by: Hao Wu <wuhao...@google.com> --- docs/specs/ipmi.rst | 70 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 70 insertions(+) diff --git a/docs/specs/ipmi.rst b/docs/specs/ipmi.rst index e0badc7f15..b06ad74728 100644 --- a/docs/specs/ipmi.rst +++ b/docs/specs/ipmi.rst @@ -91,6 +91,76 @@ further delegated to an external emulator, or a real BMC. The ``ipmi-bmc-extern`` device has a required ``chardev`` property which specifies the communications channel to the external BMC. +Baseband Management Controller (BMC) emulation +============================================== + +This section is about emulation of IPMI-related devices in a System-on-Chip +(SoC) used as a Baseband Management Controller. This is not to be confused with +emulating the BMC device as seen by the main processor. + +SoCs that are designed to be used as a BMC often have dedicated hardware that +allows them to be connected to one or more of the IPMI System Interfaces. The +BMC-side hardware interface is not standardized, so each type of SoC may need +its own device implementation in QEMU, for example: + +* ``aspeed-ibt`` for emulating the Aspeed iBT peripheral. +* ``npcm7xx-kcs`` for emulating the Nuvoton NPCM7xx Host-to-BMC Keyboard + Controller Style (KCS) channels. + +.. blockdiag:: + + blockdiag bmc_ipmi { + orientation = portrait + default_group_color = "none"; + class interface [color = lightblue]; + class host [color = salmon]; + + host [color="aquamarine", label="External Host"] + + group { + orientation = portrait + + group { + orientation = portrait + + bmc-interface [class = "interface"] + npcm7xx-ipmi-kcs [class = "interface", stacked] + + bmc-interface <- npcm7xx-ipmi-kcs [hstyle = generalization]; + } + + group { + orientation = portrait + + bmc-host [class = "host"]; + bmc-host-sim [class = "host"]; + bmc-host-extern [class = "host"]; + + bmc-host <- bmc-host-sim [hstyle = generalization]; + bmc-host <- bmc-host-extern [hstyle = generalization]; + } + + bmc-interface <-> bmc-host + } + + bmc-host-extern <-> host [label="chardev"]; + } + +IPMI Host +--------- + +Mirroring the main processor emulation, the interface devices delegate +emulation of host behavior to a Host device that is a subclass of +``ipmi-core``. This type of device is called a Host because that's what it +looks like to the BMC guest software. + +The host behavior may be further delegated to an external emulator (e.g. +another QEMU VM) through the ``ipmi-bmc-client`` host implementation. This +device has a required ``chardev`` property which specifies the communications +channel to the external host and a required ``interface-client`` property which +specifies the underlying IPMI interface. The wire format is the same as for +``ipmi-bmc-extern``. + Wire protocol ============= -- 2.40.0.348.gf938b09366-goog