Re: [PATCH] x86_32: trim memory by updating e820 v3

From: Andrew Morton
Date: Sat Apr 26 2008 - 06:57:06 EST


On Tue, 22 Jan 2008 16:23:20 -0800 Yinghai Lu <Yinghai.Lu@xxxxxxx> wrote:

> [PATCH] x86_32: trim memory by updating e820 v3
>
> when mtrr is not covering all e820 table, need to trim the ram, need to update e820
>
> reuse some code for x86_64
>
> here need to add early_get_cap and use it in early_cpu_detect, and move mtrr_bp_init early
>
> need Justine to test with his special system with bug bios.
>
> Signed-off-by: Yinghai Lu <yinghai.lu@xxxxxxx>

Speaking of mtrr and e820....

Could someone please take a peek at
http://bugzilla.kernel.org/show_bug.cgi?id=10508 ?

For some reason we seem to have turned this:

[ 0.000000] BIOS-e820: 0000000000000000 - 000000000009f800 (usable)
[ 0.000000] BIOS-e820: 000000000009f800 - 00000000000a0000 (reserved)
[ 0.000000] BIOS-e820: 00000000000dc000 - 0000000000100000 (reserved)
[ 0.000000] BIOS-e820: 0000000000100000 - 00000000bf6d0000 (usable)
[ 0.000000] BIOS-e820: 00000000bf6d0000 - 00000000bf6e3000 (ACPI NVS)
[ 0.000000] BIOS-e820: 00000000bf6e3000 - 00000000c0000000 (reserved)
[ 0.000000] BIOS-e820: 00000000e0000000 - 00000000f0000000 (reserved)
[ 0.000000] BIOS-e820: 00000000fec00000 - 00000000fec10000 (reserved)
[ 0.000000] BIOS-e820: 00000000fed00000 - 00000000fed00400 (reserved)
[ 0.000000] BIOS-e820: 00000000fed14000 - 00000000fed1a000 (reserved)
[ 0.000000] BIOS-e820: 00000000fed1c000 - 00000000fed90000 (reserved)
[ 0.000000] BIOS-e820: 00000000fee00000 - 00000000fee01000 (reserved)
[ 0.000000] BIOS-e820: 00000000ff000000 - 0000000100000000 (reserved)
[ 0.000000] BIOS-e820: 0000000100000000 - 0000000140000000 (usable)

into this:

reg00: base=0xc0000000 (3072MB), size=1024MB: uncachable, count=1
reg01: base=0x00000000 ( 0MB), size=4096MB: write-back, count=1
reg02: base=0x100000000 (4096MB), size=1024MB: write-back, count=1
reg03: base=0xbf700000 (3063MB), size= 1MB: uncachable, count=1
reg04: base=0xbf800000 (3064MB), size= 8MB: uncachable, count=1

which screws up the X server's attempt to map the video memory at
0xd0000000.

Thanks.
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