[Qemu-devel] [Bug 510612] Re: sound broken in qemu 0.12.x

[Michael Tokarev]

More information about this.  The mentioned commit fixes just the
messages apparently, but not the actual problem which is elsewhere.  The
complete fix consists of 3 patches: the above in comment#7, and also
22d948a2d97434192018bdabaf0a50cda7f994be and
38cc9b607f85017b095793cab6c129bc9844f441 from qemu-kvm git tree (both
applies and applicable for 0.12 as well as 0.13).

** Bug watch added: Debian Bug tracker #588899
   http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=588899

** Also affects: qemu-kvm (Debian) via
   http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=588899
   Importance: Unknown
       Status: Unknown

** Tags added: alsa
** Tags removed: windows

-- 
sound broken in qemu 0.12.x
https://bugs.launchpad.net/bugs/510612
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Status in QEMU: New
Status in “qemu” package in Debian: New
Status in “qemu-kvm” package in Debian: Unknown

Bug description:
In qemu 0.12.x there is a jitter when sound is played by guest Windows XP SP2. 
Also there are warnings on console:

alsa: Unexpected state 1
alsa: Unexpected state 1

and qemu tries to eat 100% cpu. According to strace it polls alsa device 
continuously:

futex(0x849e60, FUTEX_WAKE_PRIVATE, 1)  = 1
select(23, [6 10 12 20 22], [18], [], {1, 0}) = 1 (out [18], left {0, 999997})
poll([{fd=18, events=POLLOUT|POLLERR|POLLNVAL}], 1, 0) = 1 ([{fd=18, 
revents=POLLOUT|POLLERR}])
write(2, "alsa: "..., 6)                = 6
write(2, "Unexpected state 1\n"..., 19) = 19

The bug appears with ac97 and es1370 guest sound devices (i didn't test others).

With OSS host sound driver there are no warnings and consumption of cpu by qemu 
is normal, but jitter in the sound is still there.