[alsa-devel] Something wrong with snd_pcm_avail_update

Lennart Poettering mznyfn at 0pointer.de
Wed Sep 24 02:19:54 CEST 2008


There seems to be something wrong with snd_pcm_update_avail() for mmap
in recent 2.6.26 kernels:

Quoting Alexander Gavrilov:

Fedora 9 with kernel exhibits a bug where
the driver decrements its hw.ptr under certain stress
conditions, or at least it appears so from debugging.

It causes alsa-lib to give absurdly huge avail numbers
to pulseaudio, which crashes it. This patch adds a
work-around to avoid such unfriendly behavior until
the bug is fixed.

As this is not a real fix, it displays a message every
time it is activated.


(see the patch attached to that bug report)

Takashi, Jaroslav, do you know anything about this?


Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net         ICQ# 11060553
http://0pointer.net/lennart/           GnuPG 0x1A015CC4

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