Re: [Qemu-devel] Stack corruption problem with SeaBIOS/gPXE under QEMU

[Gleb Natapov <gleb@redhat.com>]

On Wed, Nov 18, 2009 at 10:49:37AM +0100, Alexander Graf wrote:
> 
> On 18.11.2009, at 10:39, Gleb Natapov wrote:
> 
> >On Mon, Nov 16, 2009 at 09:26:20PM -0500, Kevin O'Connor wrote:
> >>On Mon, Nov 16, 2009 at 04:02:20PM +0200, Avi Kivity wrote:
> >>>>Something that is likely related, I am seeing reboot failures in
> >>>>seabios's pmm_free.  Immediately after loading gpxe, seabios
> >>>>is in an
> >>>>endless loop there, likely due to memory corruption.
> >>>>
> >>>>This is with -smp 2, rebooting Fedora 9 after installation.
> >>>
> >>>With gpxe disabled, rebooting works as expected.
> >>>
> >>>Note the tests were performed with the stack at 64K to avoid
> >>>triggering
> >>>the known issue.
> >>
> >>Hi Avi,
> >>
> >>Can you send the full qemu command line that you used?  I can't seem
> >>to reproduce this on my setup.
> >>
> >>I do see an issue if SeaBIOS's reboot vector is called (eg, by using
> >>"sendkey ctrl-alt-delete" while still in the bios) because seabios
> >>allows gpxe to modify itself, and on a seabios only reboot the gpxe
> >>rom isn't recopied and gpxe therefore gets confused.  However, on a
> >>linux invoked reboot, it looks like a full machine reset occurs and
> >>qemu recopies the gpxe rom, so that doesn't seem to be an issue.
> >>
> >Do we have the same problem with tpr patching rom (vapic,bin)? It
> >modifies
> >itself too.
> 
> Are you sure vapic.bin still works with SeaBIOS? I've had to modify
> the multiboot and linuxboot code to write to the stack because the
> code section of the option rom was read only.
> 
I tested it with SeaBIOS and it worked. Actually vapic.bin doesn't modifies
itself during BIOS run. Part of vapic.bin are modified by QEMU and other
part are modified during Windows run.

--
			Gleb.