Re: [Qemu-devel] [TestDays] s390x emulation error

["Andreas Färber" <afaerber@suse.de>]

Am 10.11.2011 12:29, schrieb Andreas Färber:
> Am 10.11.2011 11:32, schrieb Alexander Graf:
>>
>> On 10.11.2011, at 10:53, Andreas Färber <afaerber@suse.de> wrote:
>>
>>> Is there a known issue with running multiple instances of
>>> qemu-system-s390x? I got a hang on openSUSE 12.1 RC2 x86_64 host:
>>>
>>> 0x00007f0de7f698d4 in __lll_lock_wait () from /lib64/libpthread.so.0
>>> (gdb) bt
>>> #0  0x00007f0de7f698d4 in __lll_lock_wait () from /lib64/libpthread.so.0
>>> #1  0x00007f0de7f651c5 in _L_lock_883 () from /lib64/libpthread.so.0
>>> #2  0x00007f0de7f6501a in pthread_mutex_lock () from /lib64/libpthread.so.0
>>> #3  0x000000000048b4a9 in qemu_mutex_lock (mutex=<optimized out>)
>>>    at /home/andreas/QEMU/qemu/qemu-thread-posix.c:54
>>> #4  0x00000000004cd3df in qemu_mutex_lock_iothread ()
>>>    at /home/andreas/QEMU/qemu/cpus.c:843
>>> #5  0x0000000000467580 in main_loop_wait (nonblocking=<optimized out>)
>>>    at /home/andreas/QEMU/qemu/main-loop.c:459
>>> #6  0x0000000000408984 in main_loop () at /home/andreas/QEMU/qemu/vl.c:1481
>>> #7  main (argc=<optimized out>, argv=<optimized out>, envp=<optimized out>)
>>>    at /home/andreas/QEMU/qemu/vl.c:3474
>>>
>>> Key presses didn't work, SDL window doesn't close, at 99.9% CPU.
>>
>> Huh? This is all generic code O_o. And no, it's not a known issue.
> 
> Hm, reproducable by running
> 
> $ s390x-softmmu/qemu-system-s390x
> 
> (without arguments) on s390-next branch.
> 
> I get compat_monitor0 console, but monitor or switching to real console
> don't work and neither does closing. Same backtrace.

Same in my WIP qemu-system-rl78.

I found that the following main-loop change works around it for s390x
and rl78 but breaks x86_64 SeaBIOS boot. Paolo, any ideas?

diff --git a/main-loop.c b/main-loop.c
index 60e9748..2ab5023 100644
--- a/main-loop.c
+++ b/main-loop.c
@@ -460,7 +460,7 @@ int main_loop_wait(int nonblocking)
     }

     glib_select_poll(&rfds, &wfds, &xfds, (ret < 0));
-    qemu_iohandler_poll(&rfds, &wfds, &xfds, ret);
+    qemu_iohandler_poll(&rfds, &wfds, &xfds, (ret < 0));
 #ifdef CONFIG_SLIRP
     slirp_select_poll(&rfds, &wfds, &xfds, (ret < 0));
 #endif

A deadlock between iothread and main?

Andreas

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