Re: Inconsistent fixed MTRR settings in BP6

Erich Boleyn (erich@uruk.org)
Tue, 30 Nov 1999 00:13:10 -0800


Peter Bell <bellp@OIT.EDU> wrote:

> I have to second that question on the error message
>
> mtrr: your CPUs had inconsistent fixed MTRR settings
> mtrr: probably your BIOS does not setup all CPUs
>
> does anyone know much about this?

This means that the BIOS didn't set up the MTRRs (Memory Type Range
Registers) in the same way for both CPUs.

This is actually allowed in the MP BIOS definition. But it's kind of a
rotten trick to play on someone if their OS doesn't know how to take
care of it, as it usually ends up just making your system run pretty
slow, but otherwise functionally correct.

So, the OS is just warning you about it. I forget offhand, but suspect
that Linux fixes this by setting the other CPUs' MTRRs to the same as
the boot processor, which is the Right Thing to do.

--
    Erich Stefan Boleyn                      \_         <erich@uruk.org>
  Mad but Happy Scientist                      \__    http://www.uruk.org/
  Motto: "I'll live forever or die trying"        ---------------------------

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