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

From: H. Peter Anvin
Date: Thu Jan 24 2008 - 20:52:54 EST


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...

-hpa
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