Re: Suspected regression in "x86: extend e820 ealy_res support 32bit"

From: Jeremy Fitzhardinge
Date: Wed May 21 2008 - 18:01:48 EST

Yinghai Lu wrote:
On Wed, May 21, 2008 at 11:19 AM, Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:
I'm seeing a crash in current x86.git tip/auto-latest when booting under
Xen. The crash is rather early, but it's in __alloc_bootmem_core() in the
final memset clear. Apparently the allocator is returning a bad page.

This points to changes in the setup of the bootmem allocator, and the
changes "x86: extend e820 ealy_res support 32bit" make to
arch/x86/kernel/setup_32.c:setup_bootmem_allocator() looks like the most
likely suspect. Unfortunately its a rather large patch which is not easy to
revert, so I haven't actually confirmed this yet.

thanks. please check the attached patch

Thanks for the quick response. I definitely confirmed that "x86: extend e820 ealy_res support 32bit" is the source of the regression, and reverting the change makes the system bootable under Xen. (My previous reversion failed because I didn't actually have the x86.git changes applied :-/)

This patch generates the warning:

CC arch/x86/kernel/setup_32.o
/home/jeremy/hg/xen/paravirt/linux/arch/x86/kernel/setup_32.c: In
function âsetup_archâ:
warning: âbootmap_sizeâ is used uninitialized in this function

but I think it's just that the panic() message still uses it before its assigned.

Hm, and it also fails to fix the problem. I'm still seeing the virtual machine crash in the same way.

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