Re: [PATCH v2] x86: mtrr: don't modify RdDram/WrDram bits of fixed MTRRs

Ingo Molnar
2009-03-13T01:59:44Z

* Andreas Herrmann <andreas.herrmann3@amd.com> wrote:

> Impact: bug fix + BIOS workaround

> Change to previous version:
> I slightly modified the log message (e.g. addition of FW_WARN).
>
> Please consider to apply this patch for .29.

i've applied it to tip:x86/mtrr, thanks Andreas.

I've add a -stable backport tag - so if it's problem-free it
should show up in .29.1.

It is not completely clear what the impact of this fix is. What
types of problems are such incoherent MTRR settings causing in
practice? Boot hang? S2RAM failures? Performance problems?

Without knowing the exact impact we cannot apply it this late in
the .29.0 cycle - and MTRR code change are dangerous in any case
so even if we knew the exact scope and impact we'd probably not
do it in .29.

Ingo