Garrett D'Amore wrote: > Paul Jakma wrote: > >> On Wed, 17 Oct 2007, Garrett D'Amore wrote: >> >>> I think this is only true when the host operating system is not >>> running. If the host OS is running, then gigabit should be fine. >> >> >> So what happens when the host OS stops running suddenly (crash or >> hardware fault)? > > > The AMT firmware is supposed to figure this out. I think the NIC drops > down to 100Mbps mode. I'm not sure exactly how this monitoring is > done. I imagine there is a watchdog register that is tickled or somesuch.
There is a separate ARC processor at the North Bridge of the PC motherboard. This processor runs AMT which can act like a watchdog to monitor the host OS. >> >> Further, it seems the host OS needs to re-enable the ARP intercept in >> the NIC hardware on shutdown. I'm very curious if that means a sudden >> host stop will render the AMT LOM inaccessible in short order.. > > > No, AMT is precisely designed the way it is to deal with this case. If > you crash your operating system, within a second or two (or > thereabouts) AMT figures out that the host is out to lunch, and the ME > takes over. > > In case anyone is curious, the ME/AMT environment is really like an > embedded service processor, and as such, traffic to it is probably not > terribly common. It has a serial port/console shunt, and also provides > some other features like remote host reset capability, etc. > In addition, there is a non-volatile memory area, in case of host OS crash, "the last words" can be saved there for postmortem. -- David Chieu > -- Garrett >
