On May 10, 2015, at 10:54 AM, Paolo Bonzini wrote: > > > On 06/05/2015 18:40, Programmingkid wrote: >> When I try to use the pcspk sound hardware, QEMU freezes and uses >> 100% of the cpu time. This is the command I use: >> >> qemu-system-i386 -cdrom <anything you wan here> -soundhw pcspk >> >> This looks like a deadlock situation because some unknown code called >> qemu_mutex_lock(). Here is the stack trace at the freeze: >> >> (gdb) bt #0 0x00007fff824e2db6 in semaphore_wait_trap () #1 >> 0x00007fff824e8417 in pthread_mutex_lock () #2 0x0000000100267199 in >> qemu_mutex_lock (mutex=<value temporarily unavailable, due to >> optimizations>) at util/qemu-thread-posix.c:73 #3 0x003c44016e95153b >> in ?? () >> >> My host is Mac OS 10.6.8. My guest isn't really anything. I have used >> Windows XP before but it isn't necessary to reproduce the problem. >> >> The ?? is what appears to be the problem. I can't even print >> instructions at that address. Any ideas as to what is calling the >> qemu_mutex_lock() function could help. > > Reproduced with a FreeDOS image from QEMU Advent Calendar. It locks up > as soon as you type "beep". > > It works with the PulseAudio and ALSA backends, but it doesn't with the > SDL backend, even on Linux. > > Also, it deadlocks even with KVM enabled. > > Paolo
Thank you very much for finding this out. Any theories as to what is wrong? This is my list of theories: - Compiler bug - Bug with a dependency - Host operating system bug/untrue assumption - Emulated sound cards not implementing some required functionality - Missing/broken deadlock prevention code
