Re: [PATCH] x86: trim ram need to check if mtrr is there v2

From: Jeremy Fitzhardinge
Date: Fri Jan 25 2008 - 02:59:59 EST


Yinghai Lu wrote:
[PATCH] x86: trim ram need to check if mtrr is there v2

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
***************
H. Peter Anvin wrote:
Looks like the code doesn't check that the CPU *has* MTRRs...

so check it mtrr is there, also check if mem less 4G and is AMD as early

Thanks, this gets me to usermode under kvm.

J
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