[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Xen-devel] [PATCH] x86/boot: Fix BIOS memory corruption on certain IBM systems
On 12/03/2013 08:34 PM, Andrew Cooper wrote:
IBM System x3530 M4 BIOSes (including the latest available at the time of this
patch) will corrupt a byte at physical address 0x105ff1 to the value of 0x86
if %esp has the value 0x00080000 when issuing an `int $0x15 (ax=0xec00)` to
inform the system about our intended operating mode.
Xen gets unhappy when the bootloader has placed it's .text section in over
this specific region of RAM.
After dropping into 16bit mode, initialise as much state as we possibly can to
sane values. This includes 0 for all the GPRs and %cs for %fs and %gs which
would otherwise be unreal segment selectors.
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CC: Keir Fraser <keir@xxxxxxx>
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
---
George:
* This fixes a memory corruption issue, so counts towards both #1 and #2 as
far as a freeze exception goes.
The general rule during the code freeze is that bug fixes are exempt
from needing a freeze exception, unless the maintainers think that it's
particularly risky. I suppose one could quibble about whether this is a
"bug fix" or a "work-around for broken BIOS" though, so just in case:
Release-acked-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel
|
