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

[Gleb Natapov]

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.

> BTW, how did you change the stack location?  I've been changing
> seabios by setting BUILD_STACK_ADDR to 0x7000 (or 0xfff0) in
> src/config.h.
> 
> -Kevin
> 

--
                        Gleb.