qemu-kvm-1.0 crashes with threaded vnc server?

qemu-kvm-1.0 crashes with threaded vnc server?

[Peter Lieven]

Hi,

is anyone aware if there are still problems when enabling the threaded 
vnc server?
I saw some VMs crashing when using a qemu-kvm build with 
--enable-vnc-thread.

qemu-kvm-1.0[22646]: segfault at 0 ip 00007fec1ca7ea0b sp 
00007fec19d056d0 error 6 in libz.so.1.2.3.3[7fec1ca75000+16000]
qemu-kvm-1.0[26056]: segfault at 7f06d8d6e010 ip 00007f06e0a30d71 sp 
00007f06df035748 error 6 in libc-2.11.1.so[7f06e09aa000+17a000]

I had no time to debug further. It seems to happen shortly after 
migrating, but thats uncertain. At least the segfault in libz seems to
give a hint to VNC since I cannot image of any other part of qemu-kvm 
using libz except for VNC server.

Thanks,
Peter

Re: qemu-kvm-1.0 crashes with threaded vnc server?

[Corentin Chary]

On Thu, Feb 9, 2012 at 7:08 PM, Peter Lieven <pl@dlh.net> wrote:
> Hi,
>
> is anyone aware if there are still problems when enabling the threaded vnc
> server?
> I saw some VMs crashing when using a qemu-kvm build with
> --enable-vnc-thread.
>
> qemu-kvm-1.0[22646]: segfault at 0 ip 00007fec1ca7ea0b sp 00007fec19d056d0
> error 6 in libz.so.1.2.3.3[7fec1ca75000+16000]
> qemu-kvm-1.0[26056]: segfault at 7f06d8d6e010 ip 00007f06e0a30d71 sp
> 00007f06df035748 error 6 in libc-2.11.1.so[7f06e09aa000+17a000]
>
> I had no time to debug further. It seems to happen shortly after migrating,
> but thats uncertain. At least the segfault in libz seems to
> give a hint to VNC since I cannot image of any other part of qemu-kvm using
> libz except for VNC server.
>
> Thanks,
> Peter
>
>

Hi Peter,
I found two patches on my git tree that I sent long ago but somehow
get lost on the mailing list. I rebased the tree but did not have the
time (yet) to test them.
http://git.iksaif.net/?p=qemu.git;a=shortlog;h=refs/heads/wip
Feel free to try them. If QEMU segfault again, please send a full gdb
backtrace / valgrind trace / way to reproduce :).
Thanks,


-- 
Corentin Chary
http://xf.iksaif.net

Re: qemu-kvm-1.0 crashes with threaded vnc server?

[Peter Lieven]

Am 11.02.2012 um 09:55 schrieb Corentin Chary:

> On Thu, Feb 9, 2012 at 7:08 PM, Peter Lieven <pl@dlh.net> wrote:
>> Hi,
>> 
>> is anyone aware if there are still problems when enabling the threaded vnc
>> server?
>> I saw some VMs crashing when using a qemu-kvm build with
>> --enable-vnc-thread.
>> 
>> qemu-kvm-1.0[22646]: segfault at 0 ip 00007fec1ca7ea0b sp 00007fec19d056d0
>> error 6 in libz.so.1.2.3.3[7fec1ca75000+16000]
>> qemu-kvm-1.0[26056]: segfault at 7f06d8d6e010 ip 00007f06e0a30d71 sp
>> 00007f06df035748 error 6 in libc-2.11.1.so[7f06e09aa000+17a000]
>> 
>> I had no time to debug further. It seems to happen shortly after migrating,
>> but thats uncertain. At least the segfault in libz seems to
>> give a hint to VNC since I cannot image of any other part of qemu-kvm using
>> libz except for VNC server.
>> 
>> Thanks,
>> Peter
>> 
>> 
> 
> Hi Peter,
> I found two patches on my git tree that I sent long ago but somehow
> get lost on the mailing list. I rebased the tree but did not have the
> time (yet) to test them.
> http://git.iksaif.net/?p=qemu.git;a=shortlog;h=refs/heads/wip
> Feel free to try them. If QEMU segfault again, please send a full gdb
> backtrace / valgrind trace / way to reproduce :).
> Thanks,

Hi Corentin,

thanks for rebasing those patches. I remember that I have seen them the
last time I noticed (about 1 year ago) that the threaded VNC is crashing.
I'm on vacation this week, but I will test them next week 
and let you know if I can force a crash with them applied. If not we should
consider to include them asap.

Peter


> 
> 
> -- 
> Corentin Chary
> http://xf.iksaif.net

Re: qemu-kvm-1.0 crashes with threaded vnc server?

[Corentin Chary]

On Mon, Feb 13, 2012 at 10:24 AM, Peter Lieven <pl@dlh.net> wrote:
>
> Am 11.02.2012 um 09:55 schrieb Corentin Chary:
>
>> On Thu, Feb 9, 2012 at 7:08 PM, Peter Lieven <pl@dlh.net> wrote:
>>> Hi,
>>>
>>> is anyone aware if there are still problems when enabling the threaded vnc
>>> server?
>>> I saw some VMs crashing when using a qemu-kvm build with
>>> --enable-vnc-thread.
>>>
>>> qemu-kvm-1.0[22646]: segfault at 0 ip 00007fec1ca7ea0b sp 00007fec19d056d0
>>> error 6 in libz.so.1.2.3.3[7fec1ca75000+16000]
>>> qemu-kvm-1.0[26056]: segfault at 7f06d8d6e010 ip 00007f06e0a30d71 sp
>>> 00007f06df035748 error 6 in libc-2.11.1.so[7f06e09aa000+17a000]
>>>
>>> I had no time to debug further. It seems to happen shortly after migrating,
>>> but thats uncertain. At least the segfault in libz seems to
>>> give a hint to VNC since I cannot image of any other part of qemu-kvm using
>>> libz except for VNC server.
>>>
>>> Thanks,
>>> Peter
>>>
>>>
>>
>> Hi Peter,
>> I found two patches on my git tree that I sent long ago but somehow
>> get lost on the mailing list. I rebased the tree but did not have the
>> time (yet) to test them.
>> http://git.iksaif.net/?p=qemu.git;a=shortlog;h=refs/heads/wip
>> Feel free to try them. If QEMU segfault again, please send a full gdb
>> backtrace / valgrind trace / way to reproduce :).
>> Thanks,
>
> Hi Corentin,
>
> thanks for rebasing those patches. I remember that I have seen them the
> last time I noticed (about 1 year ago) that the threaded VNC is crashing.
> I'm on vacation this week, but I will test them next week
> and let you know if I can force a crash with them applied. If not we should
> consider to include them asap.

Hi Peter, any news on that ?



-- 
Corentin Chary
http://xf.iksaif.net

Re: qemu-kvm-1.0 crashes with threaded vnc server?

[Peter Lieven]

On 28.02.2012 09:37, Corentin Chary wrote:
> On Mon, Feb 13, 2012 at 10:24 AM, Peter Lieven<pl@dlh.net>  wrote:
>> Am 11.02.2012 um 09:55 schrieb Corentin Chary:
>>
>>> On Thu, Feb 9, 2012 at 7:08 PM, Peter Lieven<pl@dlh.net>  wrote:
>>>> Hi,
>>>>
>>>> is anyone aware if there are still problems when enabling the threaded vnc
>>>> server?
>>>> I saw some VMs crashing when using a qemu-kvm build with
>>>> --enable-vnc-thread.
>>>>
>>>> qemu-kvm-1.0[22646]: segfault at 0 ip 00007fec1ca7ea0b sp 00007fec19d056d0
>>>> error 6 in libz.so.1.2.3.3[7fec1ca75000+16000]
>>>> qemu-kvm-1.0[26056]: segfault at 7f06d8d6e010 ip 00007f06e0a30d71 sp
>>>> 00007f06df035748 error 6 in libc-2.11.1.so[7f06e09aa000+17a000]
>>>>
>>>> I had no time to debug further. It seems to happen shortly after migrating,
>>>> but thats uncertain. At least the segfault in libz seems to
>>>> give a hint to VNC since I cannot image of any other part of qemu-kvm using
>>>> libz except for VNC server.
>>>>
>>>> Thanks,
>>>> Peter
>>>>
>>>>
>>> Hi Peter,
>>> I found two patches on my git tree that I sent long ago but somehow
>>> get lost on the mailing list. I rebased the tree but did not have the
>>> time (yet) to test them.
>>> http://git.iksaif.net/?p=qemu.git;a=shortlog;h=refs/heads/wip
>>> Feel free to try them. If QEMU segfault again, please send a full gdb
>>> backtrace / valgrind trace / way to reproduce :).
>>> Thanks,
>> Hi Corentin,
>>
>> thanks for rebasing those patches. I remember that I have seen them the
>> last time I noticed (about 1 year ago) that the threaded VNC is crashing.
>> I'm on vacation this week, but I will test them next week
>> and let you know if I can force a crash with them applied. If not we should
>> consider to include them asap.
> Hi Peter, any news on that ?
sorry, i had much trouble debugging nasty slow windows vm problems last 
2 weeks.
but its still on my list. i'll keep you all posted.

peter

>
>

Re: qemu-kvm-1.0 crashes with threaded vnc server?

[Peter Lieven]

On 11.02.2012 09:55, Corentin Chary wrote:
> On Thu, Feb 9, 2012 at 7:08 PM, Peter Lieven<pl@dlh.net>  wrote:
>> Hi,
>>
>> is anyone aware if there are still problems when enabling the threaded vnc
>> server?
>> I saw some VMs crashing when using a qemu-kvm build with
>> --enable-vnc-thread.
>>
>> qemu-kvm-1.0[22646]: segfault at 0 ip 00007fec1ca7ea0b sp 00007fec19d056d0
>> error 6 in libz.so.1.2.3.3[7fec1ca75000+16000]
>> qemu-kvm-1.0[26056]: segfault at 7f06d8d6e010 ip 00007f06e0a30d71 sp
>> 00007f06df035748 error 6 in libc-2.11.1.so[7f06e09aa000+17a000]
>>
>> I had no time to debug further. It seems to happen shortly after migrating,
>> but thats uncertain. At least the segfault in libz seems to
>> give a hint to VNC since I cannot image of any other part of qemu-kvm using
>> libz except for VNC server.
>>
>> Thanks,
>> Peter
>>
>>
> Hi Peter,
> I found two patches on my git tree that I sent long ago but somehow
> get lost on the mailing list. I rebased the tree but did not have the
> time (yet) to test them.
> http://git.iksaif.net/?p=qemu.git;a=shortlog;h=refs/heads/wip
> Feel free to try them. If QEMU segfault again, please send a full gdb
> backtrace / valgrind trace / way to reproduce :).
> Thanks,
>
I have seen no more crashes with these to patches applied. I would suggest
it would be good to push them to the master repository.

Thank you,
Peter

Re: qemu-kvm-1.0 crashes with threaded vnc server?

[Corentin Chary]

On Tue, Mar 13, 2012 at 12:29 PM, Peter Lieven <pl@dlh.net> wrote:
> On 11.02.2012 09:55, Corentin Chary wrote:
>>
>> On Thu, Feb 9, 2012 at 7:08 PM, Peter Lieven<pl@dlh.net>  wrote:
>>>
>>> Hi,
>>>
>>> is anyone aware if there are still problems when enabling the threaded
>>> vnc
>>> server?
>>> I saw some VMs crashing when using a qemu-kvm build with
>>> --enable-vnc-thread.
>>>
>>> qemu-kvm-1.0[22646]: segfault at 0 ip 00007fec1ca7ea0b sp
>>> 00007fec19d056d0
>>> error 6 in libz.so.1.2.3.3[7fec1ca75000+16000]
>>> qemu-kvm-1.0[26056]: segfault at 7f06d8d6e010 ip 00007f06e0a30d71 sp
>>> 00007f06df035748 error 6 in libc-2.11.1.so[7f06e09aa000+17a000]
>>>
>>> I had no time to debug further. It seems to happen shortly after
>>> migrating,
>>> but thats uncertain. At least the segfault in libz seems to
>>> give a hint to VNC since I cannot image of any other part of qemu-kvm
>>> using
>>> libz except for VNC server.
>>>
>>> Thanks,
>>> Peter
>>>
>>>
>> Hi Peter,
>> I found two patches on my git tree that I sent long ago but somehow
>> get lost on the mailing list. I rebased the tree but did not have the
>> time (yet) to test them.
>> http://git.iksaif.net/?p=qemu.git;a=shortlog;h=refs/heads/wip
>> Feel free to try them. If QEMU segfault again, please send a full gdb
>> backtrace / valgrind trace / way to reproduce :).
>> Thanks,
>>
> I have seen no more crashes with these to patches applied. I would suggest
> it would be good to push them to the master repository.
>
> Thank you,
> Peter
>

Ccing Alexander,


-- 
Corentin Chary
http://xf.iksaif.net

Re: qemu-kvm-1.0 crashes with threaded vnc server?

[Alexander Graf]

On 13.03.2012, at 16:05, Corentin Chary wrote:

> On Tue, Mar 13, 2012 at 12:29 PM, Peter Lieven <pl@dlh.net> wrote:
>> On 11.02.2012 09:55, Corentin Chary wrote:
>>> 
>>> On Thu, Feb 9, 2012 at 7:08 PM, Peter Lieven<pl@dlh.net>  wrote:
>>>> 
>>>> Hi,
>>>> 
>>>> is anyone aware if there are still problems when enabling the threaded
>>>> vnc
>>>> server?
>>>> I saw some VMs crashing when using a qemu-kvm build with
>>>> --enable-vnc-thread.
>>>> 
>>>> qemu-kvm-1.0[22646]: segfault at 0 ip 00007fec1ca7ea0b sp
>>>> 00007fec19d056d0
>>>> error 6 in libz.so.1.2.3.3[7fec1ca75000+16000]
>>>> qemu-kvm-1.0[26056]: segfault at 7f06d8d6e010 ip 00007f06e0a30d71 sp
>>>> 00007f06df035748 error 6 in libc-2.11.1.so[7f06e09aa000+17a000]
>>>> 
>>>> I had no time to debug further. It seems to happen shortly after
>>>> migrating,
>>>> but thats uncertain. At least the segfault in libz seems to
>>>> give a hint to VNC since I cannot image of any other part of qemu-kvm
>>>> using
>>>> libz except for VNC server.
>>>> 
>>>> Thanks,
>>>> Peter
>>>> 
>>>> 
>>> Hi Peter,
>>> I found two patches on my git tree that I sent long ago but somehow
>>> get lost on the mailing list. I rebased the tree but did not have the
>>> time (yet) to test them.
>>> http://git.iksaif.net/?p=qemu.git;a=shortlog;h=refs/heads/wip
>>> Feel free to try them. If QEMU segfault again, please send a full gdb
>>> backtrace / valgrind trace / way to reproduce :).
>>> Thanks,
>>> 
>> I have seen no more crashes with these to patches applied. I would suggest
>> it would be good to push them to the master repository.
>> 
>> Thank you,
>> Peter
>> 
> 
> Ccing Alexander,

Ah, cool. Corentin, I think you're right now the closest thing we have to a maintainer for VNC. Could you please just send out a pull request for those?


Alex

Re: qemu-kvm-1.0 crashes with threaded vnc server?

[Peter Lieven]

On 13.03.2012 16:06, Alexander Graf wrote:
> On 13.03.2012, at 16:05, Corentin Chary wrote:
>
>> On Tue, Mar 13, 2012 at 12:29 PM, Peter Lieven<pl@dlh.net>  wrote:
>>> On 11.02.2012 09:55, Corentin Chary wrote:
>>>> On Thu, Feb 9, 2012 at 7:08 PM, Peter Lieven<pl@dlh.net>   wrote:
>>>>> Hi,
>>>>>
>>>>> is anyone aware if there are still problems when enabling the threaded
>>>>> vnc
>>>>> server?
>>>>> I saw some VMs crashing when using a qemu-kvm build with
>>>>> --enable-vnc-thread.
>>>>>
>>>>> qemu-kvm-1.0[22646]: segfault at 0 ip 00007fec1ca7ea0b sp
>>>>> 00007fec19d056d0
>>>>> error 6 in libz.so.1.2.3.3[7fec1ca75000+16000]
>>>>> qemu-kvm-1.0[26056]: segfault at 7f06d8d6e010 ip 00007f06e0a30d71 sp
>>>>> 00007f06df035748 error 6 in libc-2.11.1.so[7f06e09aa000+17a000]
>>>>>
>>>>> I had no time to debug further. It seems to happen shortly after
>>>>> migrating,
>>>>> but thats uncertain. At least the segfault in libz seems to
>>>>> give a hint to VNC since I cannot image of any other part of qemu-kvm
>>>>> using
>>>>> libz except for VNC server.
>>>>>
>>>>> Thanks,
>>>>> Peter
>>>>>
>>>>>
>>>> Hi Peter,
>>>> I found two patches on my git tree that I sent long ago but somehow
>>>> get lost on the mailing list. I rebased the tree but did not have the
>>>> time (yet) to test them.
>>>> http://git.iksaif.net/?p=qemu.git;a=shortlog;h=refs/heads/wip
>>>> Feel free to try them. If QEMU segfault again, please send a full gdb
>>>> backtrace / valgrind trace / way to reproduce :).
>>>> Thanks,
>>>>
>>> I have seen no more crashes with these to patches applied. I would suggest
>>> it would be good to push them to the master repository.
>>>
>>> Thank you,
>>> Peter
>>>
>> Ccing Alexander,
> Ah, cool. Corentin, I think you're right now the closest thing we have to a maintainer for VNC. Could you please just send out a pull request for those?
hi all,

i suspect there is still a problem with the threaded vnc server. its 
just a guess, but we saw a resonable number of vms hanging in the
last weeks. hanging meaning the emulation is stopped and the qemu-kvm 
process does no longer react, not on monitor, not on vnc, not on qmp.
why i suspect the threaded vnc server is that in all cases we have 
analyzed this happened with an open vnc session and only on nodes with 
the threaded vnc server
enabled. it might also be the case that this happens at a resolution 
change. is there anything known or has someone an idea?

we are running qemu-kvm 1.0.1 with

   vnc: don't mess up with iohandlers in the vnc thread

   vnc: Limit r/w access to size of allocated memory

compiled in.

unfortunately, i was not yet able to reproduce this with a debugger 
attached.

thanks,
peter

>
> Alex
>

Re: qemu-kvm-1.0 crashes with threaded vnc server?

[Corentin Chary]

[-- Attachment #1: Type: text/plain, Size: 3329 bytes --]

Please use "gdb -p <pid>" to attach qemu when stuck and use it to dump a
full backtrace. Note that I never tested qemu-kvm and the vnc code was
originally not written for it, so the locking stuff may be broken if the
codebase differs from upstream qemu too much.
Le 26 juin 2012 17:02, "Peter Lieven" <pl@dlhnet.de> a écrit :

> On 13.03.2012 16:06, Alexander Graf wrote:
>
>> On 13.03.2012, at 16:05, Corentin Chary wrote:
>>
>>  On Tue, Mar 13, 2012 at 12:29 PM, Peter Lieven<pl@dlh.net>  wrote:
>>>
>>>> On 11.02.2012 09:55, Corentin Chary wrote:
>>>>
>>>>> On Thu, Feb 9, 2012 at 7:08 PM, Peter Lieven<pl@dlh.net>   wrote:
>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> is anyone aware if there are still problems when enabling the threaded
>>>>>> vnc
>>>>>> server?
>>>>>> I saw some VMs crashing when using a qemu-kvm build with
>>>>>> --enable-vnc-thread.
>>>>>>
>>>>>> qemu-kvm-1.0[22646]: segfault at 0 ip 00007fec1ca7ea0b sp
>>>>>> 00007fec19d056d0
>>>>>> error 6 in libz.so.1.2.3.3[7fec1ca75000+**16000]
>>>>>> qemu-kvm-1.0[26056]: segfault at 7f06d8d6e010 ip 00007f06e0a30d71 sp
>>>>>> 00007f06df035748 error 6 in libc-2.11.1.so[7f06e09aa000+**17a000]
>>>>>>
>>>>>> I had no time to debug further. It seems to happen shortly after
>>>>>> migrating,
>>>>>> but thats uncertain. At least the segfault in libz seems to
>>>>>> give a hint to VNC since I cannot image of any other part of qemu-kvm
>>>>>> using
>>>>>> libz except for VNC server.
>>>>>>
>>>>>> Thanks,
>>>>>> Peter
>>>>>>
>>>>>>
>>>>>>  Hi Peter,
>>>>> I found two patches on my git tree that I sent long ago but somehow
>>>>> get lost on the mailing list. I rebased the tree but did not have the
>>>>> time (yet) to test them.
>>>>> http://git.iksaif.net/?p=qemu.**git;a=shortlog;h=refs/heads/**wip<http://git.iksaif.net/?p=qemu.git;a=shortlog;h=refs/heads/wip>
>>>>> Feel free to try them. If QEMU segfault again, please send a full gdb
>>>>> backtrace / valgrind trace / way to reproduce :).
>>>>> Thanks,
>>>>>
>>>>>  I have seen no more crashes with these to patches applied. I would
>>>> suggest
>>>> it would be good to push them to the master repository.
>>>>
>>>> Thank you,
>>>> Peter
>>>>
>>>>  Ccing Alexander,
>>>
>> Ah, cool. Corentin, I think you're right now the closest thing we have to
>> a maintainer for VNC. Could you please just send out a pull request for
>> those?
>>
> hi all,
>
> i suspect there is still a problem with the threaded vnc server. its just
> a guess, but we saw a resonable number of vms hanging in the
> last weeks. hanging meaning the emulation is stopped and the qemu-kvm
> process does no longer react, not on monitor, not on vnc, not on qmp.
> why i suspect the threaded vnc server is that in all cases we have
> analyzed this happened with an open vnc session and only on nodes with the
> threaded vnc server
> enabled. it might also be the case that this happens at a resolution
> change. is there anything known or has someone an idea?
>
> we are running qemu-kvm 1.0.1 with
>
>  vnc: don't mess up with iohandlers in the vnc thread
>
>  vnc: Limit r/w access to size of allocated memory
>
> compiled in.
>
> unfortunately, i was not yet able to reproduce this with a debugger
> attached.
>
> thanks,
> peter
>
>
>> Alex
>>
>>
>

[-- Attachment #2: Type: text/html, Size: 4406 bytes --]

Re: qemu-kvm-1.0 crashes with threaded vnc server?

[Peter Lieven]

[-- Attachment #1: Type: text/plain, Size: 4600 bytes --]

On 28.06.2012 12:18, Corentin Chary wrote:
>
> Please use "gdb -p <pid>" to attach qemu when stuck and use it to dump 
> a full backtrace. Note that I never tested qemu-kvm and the vnc code 
> was originally not written for it, so the locking stuff may be broken 
> if the codebase differs from upstream qemu too much.
>
Hi Corentin,

it seems that this issue is not caused by the threaded vnc server. The 
race condition is also reproducible if the threaded vnc server is 
deactivated.

Sorry for the noise.

Peter

> Le 26 juin 2012 17:02, "Peter Lieven" <pl@dlhnet.de 
> <mailto:pl@dlhnet.de>> a écrit :
>
>     On 13.03.2012 16:06, Alexander Graf wrote:
>
>         On 13.03.2012, at 16:05, Corentin Chary wrote:
>
>             On Tue, Mar 13, 2012 at 12:29 PM, Peter Lieven<pl@dlh.net
>             <mailto:pl@dlh.net>>  wrote:
>
>                 On 11.02.2012 09:55, Corentin Chary wrote:
>
>                     On Thu, Feb 9, 2012 at 7:08 PM, Peter
>                     Lieven<pl@dlh.net <mailto:pl@dlh.net>>   wrote:
>
>                         Hi,
>
>                         is anyone aware if there are still problems
>                         when enabling the threaded
>                         vnc
>                         server?
>                         I saw some VMs crashing when using a qemu-kvm
>                         build with
>                         --enable-vnc-thread.
>
>                         qemu-kvm-1.0[22646]: segfault at 0 ip
>                         00007fec1ca7ea0b sp
>                         00007fec19d056d0
>                         error 6 in libz.so.1.2.3.3[7fec1ca75000+16000]
>                         qemu-kvm-1.0[26056]: segfault at 7f06d8d6e010
>                         ip 00007f06e0a30d71 sp
>                         00007f06df035748 error 6 in libc-2.11.1.so
>                         <http://libc-2.11.1.so>[7f06e09aa000+17a000]
>
>                         I had no time to debug further. It seems to
>                         happen shortly after
>                         migrating,
>                         but thats uncertain. At least the segfault in
>                         libz seems to
>                         give a hint to VNC since I cannot image of any
>                         other part of qemu-kvm
>                         using
>                         libz except for VNC server.
>
>                         Thanks,
>                         Peter
>
>
>                     Hi Peter,
>                     I found two patches on my git tree that I sent
>                     long ago but somehow
>                     get lost on the mailing list. I rebased the tree
>                     but did not have the
>                     time (yet) to test them.
>                     http://git.iksaif.net/?p=qemu.git;a=shortlog;h=refs/heads/wip
>                     Feel free to try them. If QEMU segfault again,
>                     please send a full gdb
>                     backtrace / valgrind trace / way to reproduce :).
>                     Thanks,
>
>                 I have seen no more crashes with these to patches
>                 applied. I would suggest
>                 it would be good to push them to the master repository.
>
>                 Thank you,
>                 Peter
>
>             Ccing Alexander,
>
>         Ah, cool. Corentin, I think you're right now the closest thing
>         we have to a maintainer for VNC. Could you please just send
>         out a pull request for those?
>
>     hi all,
>
>     i suspect there is still a problem with the threaded vnc server.
>     its just a guess, but we saw a resonable number of vms hanging in the
>     last weeks. hanging meaning the emulation is stopped and the
>     qemu-kvm process does no longer react, not on monitor, not on vnc,
>     not on qmp.
>     why i suspect the threaded vnc server is that in all cases we have
>     analyzed this happened with an open vnc session and only on nodes
>     with the threaded vnc server
>     enabled. it might also be the case that this happens at a
>     resolution change. is there anything known or has someone an idea?
>
>     we are running qemu-kvm 1.0.1 with
>
>      vnc: don't mess up with iohandlers in the vnc thread
>
>      vnc: Limit r/w access to size of allocated memory
>
>     compiled in.
>
>     unfortunately, i was not yet able to reproduce this with a
>     debugger attached.
>
>     thanks,
>     peter
>
>
>         Alex
>
>


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