Re: [Xen-users] qemu-dm crashing under 3.1

["Daniel P. Berrange" <berrange@xxxxxxxxxx>]

On Fri, Jun 15, 2007 at 09:19:12PM +1000, James Harper wrote:
> > 
> > That would make it a lot more readable - you could try just "objdump
> -d
> > qemu-dm" and see if that gives you a clue of which function it's in,
> but
> > using a debug build would make it much more readable.
> > 
> > You can re-build JUST qemu-dm by going to .../tools/ioemu and doing
> > "make clean all" - first modify the CFLAGS in makefile with "CFLAGS +=
> > -g" to add debug symbols. Then copy your new qemu-dm to
> > /usr/lib[64]/xen/bin on the target machine (if that's not the same
> > machine you're building the code on).
> > 
> 
> Because it was a debian build it needed a bit of persuasion...
> 
> Here's the output (excuse the line wrapping):
> 
> "
> Program received signal SIGSEGV, Segmentation fault.
> [Switching to Thread 47890972539360 (LWP 4609)]
> 0x0000000000409b25 in main_loop_wait (timeout=10)
>     at
> /usr/local/src/xen/xen-3.1-3.1.0-rc10+hg15040/debian/build/source/tools/
> ioemu/vl.c:5224
> 5224                if (ioh->fd_write && FD_ISSET(ioh->fd, &wfds)) {
> 
> (gdb) bt
> #0  0x0000000000409b25 in main_loop_wait (timeout=10)
>     at
> /usr/local/src/xen/xen-3.1-3.1.0-rc10+hg15040/debian/build/source/tools/
> ioemu/vl.c:5224
> #1  0x000000000046c041 in main_loop ()
>     at
> /usr/local/src/xen/xen-3.1-3.1.0-rc10+hg15040/debian/build/source/tools/
> ioemu/target-i386-dm/helper2.c:628
> #2  0x000000000040b6d6 in main (argc=21, argv=0x7fff2fa03468)
>     at
> /usr/local/src/xen/xen-3.1-3.1.0-rc10+hg15040/debian/build/source/tools/
> ioemu/vl.c:6903
> 
> (gdb) print ioh
> $1 = (IOHandlerRecord *) 0x9224b0
> (gdb) print ioh->fd_write
> $2 = (IOHandler *) 0x4691e0 <vnc_client_write>
> (gdb) print ioh->fd
> $3 = 9932400
> (gdb) print wfds
> $4 = {fds_bits = {0 <repeats 16 times>}}
> (gdb) print &wfds
> $5 = (fd_set *) 0x7fff2fa00760
> (gdb)
> "
> 
> The only thing that strikes me as odd is the value of ioh->fd... isn't
> that a little bit high for a fd number?

That looks like the VNC / event loop corruption bug Anthony & myself fixed
in upstream QEMU a few months back. You might want to give the attached
patch a go & see if it helps.

Regards,
Dan.
-- 
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Attachment: xen-qemu-vnc-delete.patch
Description: Text document

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