[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] Intel HDA and ALSA audio driver hogging event loop
From: |
P J P |
Subject: |
Re: [Qemu-devel] Intel HDA and ALSA audio driver hogging event loop |
Date: |
Thu, 20 Oct 2016 14:38:49 +0530 (IST) |
Hello Gerd,
+-- On Thu, 20 Oct 2016, Stefan Hajnoczi wrote --+
| A RHEL 7.2 guest sometimes hangs when I play back a wav file on the
| Intel HDA emulated sound card using the QEMU ALSA audio driver.
|
| intel_hda_xfer() transfers samples between the emulated card and the
| QEMU audio subsystem. The following case causes a problem:
| if (st->ctl & (1 << 26)) {
| /*
| * Wait with the next DMA xfer until the guest
| * has acked the buffer completion interrupt
| */
| return false;
| }
|
| If the guest hasn't acked the interrupt yet then Intel HDA returns
| without providing any samples. The QEMU ALSA driver keeps monitoring
| the file descriptor so the next event loop iteration will try to
| transfer samples again.
I was looking at another loop issue in 'intel_hda_xfer'
-> https://lists.gnu.org/archive/html/qemu-devel/2016-10/msg04682.html
It does not address the above case, but maybe both could be fixed together.
Thank you.
--
Prasad J Pandit / Red Hat Product Security Team
47AF CE69 3A90 54AA 9045 1053 DD13 3D32 FE5B 041F