[LinuxBIOS] SMM in LinuxBIOS

ron minnich rminnich at gmail.com
Fri Dec 29 17:03:12 CET 2006


On 12/24/06, Arvind Seshadri <arvinds+ at cs.cmu.edu> wrote:
> Hi,
> I would like to implement a piece of code as an SMM handler in LinuxBIOS.

I think the sensible way to do this is write an SMI handler that is
controlled by Linux (or other OS). BIOS code should not run once the
OS is up. There are lots of OS-dependent issues that a BIOS just can
not know about. To pick a simple example: Are you going to ensure that
your SMI handler is SMP-safe? If so, how, and for which OS? I know of
one vendor BIOS (EFI on the LLNL Thunder cluster, an itanium-based
machine, from several years ago) that was not re-entrant or SMP-safe,
and it was not fun when two CPUs tried to enter this BIOS at once.

Once the OS is up, the CPU should always be under control of the OS.
So, build an SMI handler for linux -- if you really need to do this.

ron




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