[coreboot] [PATCH] Warn if we run out of MTRRs

Stefan Reinauer stepan at coresystems.de
Thu Feb 12 18:00:06 CET 2009

ron minnich wrote:
> On Thu, Feb 12, 2009 at 8:35 AM, Stefan Reinauer <stepan at coresystems.de> wrote:
>> I'm not getting tired of repeating myself.:There should not be a reason
>> to un-cache the upper SMM area, or the problem is elsewhere. There is
>> definitely no issue with any of my SMM code, and there is no other SMM
>> code in the public tree or on the mailing list. So once that problem
>> will occur, we can solve that problem.
> I strongly agree. We've got a working cached SMM, from Stefan, so we
> know that one can cache SMM. For the counterargument that SMM can not
> be cached, we have a hint from someone that someone else had trouble
> -- and we have no code to inspect -- sorry, that's not strong enough
> evidence for me to accept that we need another change to the MTRR
> code.

Actually my SMM code is uncached, too, because it runs in ASEG. I have a
pretty clear idea what to do to get caching of the HSEG/TSEG working, if
we really ever need it. (see other mails to the list a few days ago)

Right now the SMM handler only runs when called by ACPI (as in: display
darker, display brighter buttoon pressed) or when trying to write to the
BIOS without "permission" to do so. No regular calls are made (timer
etc), so the impact of making sure we copy to HSEG and running cached
from there is probably higher than just running 2 SMM calls uncached in
the time from start-up to shut-down.

But let's get SMM for another platform into the tree and see what's best


coresystems GmbH • Brahmsstr. 16 • D-79104 Freiburg i. Br.
      Tel.: +49 761 7668825 • Fax: +49 761 7664613
Email: info at coresystems.dehttp://www.coresystems.de/
Registergericht: Amtsgericht Freiburg • HRB 7656
Geschäftsführer: Stefan Reinauer • Ust-IdNr.: DE245674866

More information about the coreboot mailing list