[pulseaudio-discuss] alignment trap and pulseaudio being kiled

[Arun Raghavan]

On Tue, 2011-04-05 at 10:21 +0200, Daniel Mack wrote:
> On Mon, Apr 4, 2011 at 8:45 PM, Baek Chang <baeksan at ccrma.stanford.edu> wrote:
> > Hi,
> > Trying to debug pulseaudio 0.9.22 and I am seeing some alignment trap
> > warnings from kernel
> > [ 1564.095562] Alignment trap: alsa-sink (5580) PC=0x2ab2ca3c
> > Instr=0xe1ca00d0 Address=0x2af9302a FSR 0x011
> > [ 1564.095597] Alignment trap: alsa-sink (5580) PC=0x2ab2ca68
> > Instr=0xe0ca00f8 Address=0x2af9302a FSR 0x811
> > [ 1564.113377] Alignment trap: alsa-sink (5580) PC=0x2ab2ca3c
> > Instr=0xe1ca00d0 Address=0x2af93032 FSR 0x011
> > [ 1564.122811] Alignment trap: alsa-sink (5580) PC=0x2ab2ca68
> > Instr=0xe0ca00f8 Address=0x2af93032 FSR 0x811
> > [ 1564.132240] Alignment trap: alsa-sink (5580) PC=0x2ab2ca3c
> > Instr=0xe1ca00d0 Address=0x2af9303a FSR 0x011
> > [ 1564.141703] Alignment trap: alsa-sink (5580) PC=0x2ab2ca68
> > Instr=0xe0ca00f8 Address=0x2af9303a FSR 0x811
> > [ 1564.151195] Alignment trap: alsa-sink (5580) PC=0x2ab2ca3c
> > Instr=0xe1ca00d0 Address=0x2af93042 FSR 0x011
> > [ 1564.160625] Alignment trap: alsa-sink (5580) PC=0x2ab2ca68
> > Instr=0xe0ca00f8 Address=0x2af93042 FSR 0x811
> > [ 1564.170065] Alignment trap: alsa-sink (5580) PC=0x2ab2ca3c
> > Instr=0xe1ca00d0 Address=0x2af9304a FSR 0x011
> > I tried connecting to gdb and reproducing the issue, the problem is that
> > pulseaudio doesn't crash, but eventually terminates.
> > Any ideas on how to debug this?
> 
> You can tell your kernel to terminate processes which cause an
> alignment trap immediately: "echo 5 > /proc/cpu/alignment". That
> should make gdb stop right at the instruction causing it. Also see
> $kernelsrc/Documentation/arm/mem_alignment. But note that this setting
> is for your whole system, and not done on a per-process level.
> 
> However, I dare to doubt that the alignment trap is your problem after
> all. Such exceptions are normally just silently fixed in the
> background, and the only effect you could possibly see is performance
> drawbacks.  Anyway, it would be nice to fix them.

Also, if you haven't already, do take a look at
http://pulseaudio.org/wiki/Community#BugsPatchesTranslations for
instructions on running PulseAudio in gdb.

-- Arun