Re: x86.git: mtrr trimming removes all memory under kvm

From: Yinghai Lu
Date: Thu Jan 24 2008 - 21:05:42 EST


On Thursday 24 January 2008 05:49:00 pm H. Peter Anvin wrote:
> Jeremy Fitzhardinge wrote:
> > When booting a current x86.git kernel under kvm, I get this:
> >
> > (qemu) Linux version 2.6.24-rc8 (jeremy@ezr) (gcc version 4.1.2 20070925
> > (Red Hat 4.1.2-33)) #1928 SMP PREEMPT Thu Jan 24 17:09:04 PST 2008
> > early_ioremap_init()
> > BIOS-provided physical RAM map:
> > BIOS-e820: 0000000000000000 - 000000000009fc00 (usable)
> > BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved)
> > BIOS-e820: 00000000000e8000 - 0000000000100000 (reserved)
> > BIOS-e820: 0000000000100000 - 000000001fff0000 (usable)
> > BIOS-e820: 000000001fff0000 - 0000000020000000 (ACPI data)
> > BIOS-e820: 00000000fffc0000 - 0000000100000000 (reserved)
> > console [earlyser0] enabled
> > 0MB HIGHMEM available.
> > 511MB LOWMEM available.
> > Scan SMP from c0000000 for 1024 bytes.
> > Scan SMP from c009fc00 for 1024 bytes.
> > Scan SMP from c00f0000 for 65536 bytes.
> > Scan SMP from c009fc00 for 1024 bytes.
> > ***************
> > **** WARNING: likely BIOS bug
> > **** MTRRs don't cover all of memory, trimmed 131056 pages
> > ***************
>
> Looks like the code doesn't check that the CPU *has* MTRRs...
>

on 32 bit, max_pfn is supposed to be 0?

will look at it.

YH

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