[Qemu-devel] QEMU 0.8.1 VNC: Segfault on closing

[Qemu-devel] QEMU 0.8.1 VNC: Segfault on closing

[Michael McConnell]

When I try to use QEMU's VNC server, every time I close the connection it
segfaults.  So far I've been unable to trace the cause of this (gdb appears
to be next to useless at tracing the execution), but it is totally
repeatable.

Running with kqemu 1.3.0pre7 in -kernel-kqemu with Windows XP as the guest 
operating system, the host is an Athlon XP2000+ running kernel 2.6.14, and 
glibc 2.1.3. QEMU was compiled with gcc 3.4.3.

(I tried upgrading glibc, had to restore the machine from a backup.)

Any pointers would be much appreciated...

-- Michael "Soruk" McConnell
   Eridani Star System

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Re: [Qemu-devel] QEMU 0.8.1 VNC: Segfault on closing

[Anthony Liguori]

Michael McConnell wrote:
> When I try to use QEMU's VNC server, every time I close the connection it
> segfaults.  So far I've been unable to trace the cause of this (gdb appears
> to be next to useless at tracing the execution), but it is totally
> repeatable.
>   

Can you provide more information?  What VNC client are you using?  What 
host architecture are you on?  What is the guest OS/target?

Can you provide a stack trace that leads to the seg fault?

Regards,

Anthony Liguori

> Running with kqemu 1.3.0pre7 in -kernel-kqemu with Windows XP as the guest 
> operating system, the host is an Athlon XP2000+ running kernel 2.6.14, and 
> glibc 2.1.3. QEMU was compiled with gcc 3.4.3.
>
> (I tried upgrading glibc, had to restore the machine from a backup.)
>
> Any pointers would be much appreciated...
>
> -- Michael "Soruk" McConnell
>    Eridani Star System
>
>    MailStripper - http://www.MailStripper.eu/ - SMTP spam filter
>    Mail Me Anywhere - http://www.MailMeAnywhere.com/ - Mobile email
>
>
>
> _______________________________________________
> Qemu-devel mailing list
> Qemu-devel@nongnu.org
> http://lists.nongnu.org/mailman/listinfo/qemu-devel
>   

Re: [Qemu-devel] QEMU 0.8.1 VNC: Segfault on closing

[Michael McConnell]

On Sun, 21 May 2006, Anthony Liguori wrote:

> Michael McConnell wrote:
> > When I try to use QEMU's VNC server, every time I close the connection it
> > segfaults.  So far I've been unable to trace the cause of this (gdb appears
> > to be next to useless at tracing the execution), but it is totally
> > repeatable.
> >   
> 
> Can you provide more information?  What VNC client are you using? 

TightVNC 1.2.9 - and the fault can also be triggered by just telnetting to 
the VNC port and closing the connection.

> What 
> host architecture are you on?  What is the guest OS/target?

I already gave that - REinserting immediately below.
(It was in the second paragraph, which you inserted your reply above.)
For those not familiar with AMD, the Athlon
XP2000+ is an ix86 32-bit CPU.

> > Running with kqemu 1.3.0pre7 in -kernel-kqemu with Windows XP as the guest 
> > operating system, the host is an Athlon XP2000+ running kernel 2.6.14, and 
> > glibc 2.1.3. QEMU was compiled with gcc 3.4.3.

> Can you provide a stack trace that leads to the seg fault?

GDB seems unable to - this is how it started off when analysing the core 
dump:
[soruk@Zeskia QEMU]# gdb /usr/local/bin/qemu-i386 core
GNU gdb 19991004
Copyright 1998 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i386-redhat-linux"...

Dwarf Error: Cannot handle DW_FORM_strp in DWARF reader.

Core was generated by `qemu-i386 -m 128 -sync -kernel-kqemu -boot c -net 
nic,macaddr=fe:fd:00:00:00:01'.
Program terminated with signal 11, Segmentation fault.
Reading symbols from /lib/libm.so.6...done.
Reading symbols from /usr/lib/libz.so.1...done.
Reading symbols from /usr/local/lib/libSDL-1.2.so.0...done.
Reading symbols from /lib/libpthread.so.0...done.
Reading symbols from /lib/libutil.so.1...done.
Reading symbols from /lib/libc.so.6...done.
Reading symbols from /lib/libdl.so.2...done.
Reading symbols from /usr/X11R6/lib/libX11.so.6...done.
Reading symbols from /usr/X11R6/lib/libXext.so.6...done.
Reading symbols from /lib/ld-linux.so.2...done.
#0  0x804ff4a in ?? ()
(gdb) bt
#0  0x804ff4a in ?? ()
(gdb) quit
[soruk@Zeskia QEMU]# gdb ls

I have no idea what this "dwarf error" is.

-- Michael "Soruk" McConnell
   Eridani Star System

   MailStripper - http://www.MailStripper.eu/ - SMTP spam filter
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Re: [Qemu-devel] QEMU 0.8.1 VNC: Segfault on closing

[Anthony Liguori]

Michael McConnell wrote:
> On Sun, 21 May 2006, Anthony Liguori wrote:
>
>   
>> Michael McConnell wrote:
>>     
>>> When I try to use QEMU's VNC server, every time I close the connection it
>>> segfaults.  So far I've been unable to trace the cause of this (gdb appears
>>> to be next to useless at tracing the execution), but it is totally
>>> repeatable.
>>>   
>>>       
>> Can you provide more information?  What VNC client are you using? 
>>     
>
> TightVNC 1.2.9 - and the fault can also be triggered by just telnetting to 
> the VNC port and closing the connection.
>   

Curious, I've not seen this myself and your configuration does not seem 
out of the ordinary.

Can you try with CVS and 0.8.1?  Also, make sure that you're doing a 
full build if you've built this from CVS as the dependences in the 
Makefile aren't good.

Regards,

Anthony Liguori

>   
>> What 
>> host architecture are you on?  What is the guest OS/target?
>>     
>
> I already gave that - REinserting immediately below.
> (It was in the second paragraph, which you inserted your reply above.)
> For those not familiar with AMD, the Athlon
> XP2000+ is an ix86 32-bit CPU.
>
>   
>>> Running with kqemu 1.3.0pre7 in -kernel-kqemu with Windows XP as the guest 
>>> operating system, the host is an Athlon XP2000+ running kernel 2.6.14, and 
>>> glibc 2.1.3. QEMU was compiled with gcc 3.4.3.
>>>       
>
>   
>> Can you provide a stack trace that leads to the seg fault?
>>     
>
> GDB seems unable to - this is how it started off when analysing the core 
> dump:
> [soruk@Zeskia QEMU]# gdb /usr/local/bin/qemu-i386 core
> GNU gdb 19991004
> Copyright 1998 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and you are
> welcome to change it and/or distribute copies of it under certain conditions.
> Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB.  Type "show warranty" for details.
> This GDB was configured as "i386-redhat-linux"...
>
> Dwarf Error: Cannot handle DW_FORM_strp in DWARF reader.
>
> Core was generated by `qemu-i386 -m 128 -sync -kernel-kqemu -boot c -net 
> nic,macaddr=fe:fd:00:00:00:01'.
> Program terminated with signal 11, Segmentation fault.
> Reading symbols from /lib/libm.so.6...done.
> Reading symbols from /usr/lib/libz.so.1...done.
> Reading symbols from /usr/local/lib/libSDL-1.2.so.0...done.
> Reading symbols from /lib/libpthread.so.0...done.
> Reading symbols from /lib/libutil.so.1...done.
> Reading symbols from /lib/libc.so.6...done.
> Reading symbols from /lib/libdl.so.2...done.
> Reading symbols from /usr/X11R6/lib/libX11.so.6...done.
> Reading symbols from /usr/X11R6/lib/libXext.so.6...done.
> Reading symbols from /lib/ld-linux.so.2...done.
> #0  0x804ff4a in ?? ()
> (gdb) bt
> #0  0x804ff4a in ?? ()
> (gdb) quit
> [soruk@Zeskia QEMU]# gdb ls
>
> I have no idea what this "dwarf error" is.
>
> -- Michael "Soruk" McConnell
>    Eridani Star System
>
>    MailStripper - http://www.MailStripper.eu/ - SMTP spam filter
>    Mail Me Anywhere - http://www.MailMeAnywhere.com/ - Mobile email
>
>
>
> _______________________________________________
> Qemu-devel mailing list
> Qemu-devel@nongnu.org
> http://lists.nongnu.org/mailman/listinfo/qemu-devel
>   

Re: [Qemu-devel] QEMU 0.8.1 VNC: Segfault on closing

[Michael McConnell]

On Sun, 21 May 2006, Anthony Liguori wrote:

> Michael McConnell wrote:
> > On Sun, 21 May 2006, Anthony Liguori wrote:
> >
> >   
> >> Michael McConnell wrote:
> >>     
> >>> When I try to use QEMU's VNC server, every time I close the connection it
> >>> segfaults.  So far I've been unable to trace the cause of this (gdb appears
> >>> to be next to useless at tracing the execution), but it is totally
> >>> repeatable.
> >>>       
> >> Can you provide more information?  What VNC client are you using? 
> >
> > TightVNC 1.2.9 - and the fault can also be triggered by just telnetting to 
> > the VNC port and closing the connection.
> 
> Curious, I've not seen this myself and your configuration does not seem 
> out of the ordinary.
> 
> Can you try with CVS and 0.8.1?  Also, make sure that you're doing a 
> full build if you've built this from CVS as the dependences in the 
> Makefile aren't good.

Not having quite figured out how to get CVS to work as I so rarely have to
use it (nor could I find a link on qemu.org) I tried with the
qemu-snapshot-2006-05-21_23.tar.bz2 snapshot from qemu.dad-answers.com.  And
ran into exactly the same problem.  gdb is equally useless on this build too.

-- Michael "Soruk" McConnell
   Eridani Star System

   MailStripper - http://www.MailStripper.eu/ - SMTP spam filter
   Mail Me Anywhere - http://www.MailMeAnywhere.com/ - Mobile email