Re: [Qemu-discuss] qemu hangs

[Peter Maydell]

On 16 August 2016 at 18:13, Nerijus Baliūnas
<address@hidden> wrote:
> 2016-08-16 19:58, Peter Maydell rašė:
>>
>> This is the outer process waiting for the child process to tell
>> it it's got started in os_daemonize().
>>
>> Does QEMU still hang if you don't pass it -daemonize ? If so,
>> then it will be easier to debug that.
>
>
> Yes, it still hangs:
>
> # gdb /usr/bin/qemu-system-alpha
> (gdb) r -S -no-user-config -nodefaults -nographic -M none -qmp
> unix:/var/lib/libvirt/qemu/capabilities.monitor.sock,server,nowait -pidfile
> /var/lib/libvirt/qemu/capabilities.pidfile
> Starting program: /usr/bin/qemu-system-alpha -S -no-user-config -nodefaults
> -nographic -M none -qmp
> unix:/var/lib/libvirt/qemu/capabilities.monitor.sock,server,nowait -pidfile
> /var/lib/libvirt/qemu/capabilities.pidfile
> [Thread debugging using libthread_db enabled]
> Using host libthread_db library "/lib64/libthread_db.so.1".
> [New Thread 0x7fffc9708700 (LWP 13010)]
> ^C

Has it actually hung, or is it just waiting for you to talk
QMP protocol to it on the socket ?

I think what is happening here is that libvirt starts these
QEMU processes to query them for what they support. What should
happen is that QEMU is started, libvirt talks QMP protocol to
them and then stops the QEMU processes when it's found out the
answers to its questions. I think we need to somehow get a
log of what libvirt is doing on the QMP socket to find out
whether this bug is in QEMU (eg libvirt asks it to do something
and it hangs) or in libvirt (eg libvirt doesn't tell
QEMU to quit).

Perhaps the libvirt mailing list might be able  to help?
I'm afraid I don't use it myself.

thanks
-- PMM