[alsa-devel] How to report error in _pointer function?
timur at freescale.com
Fri Aug 8 17:55:56 CEST 2008
Takashi Iwai wrote:
> What about ltrace? I'd like to know which functions are called.
This is an embedded system. I don't have ltrace or strace installed.
I suspect that this problem can easily be reproduced on any system. Just modify
the _pointer function to always return XRUN, and see what aplay does.
Anyway, I tried debugging aplay. I'm not familiar with ALSA application
programming (just drivers), so I don't know what to look for, but I did find a
I set a breakpoint on function snd_pcm_hw_writei(), which I presume is an
alsa-lib function. When I run aplay, the breakpoint is hit:
Breakpoint 1, snd_pcm_hw_writei (pcm=0x10024fd8, buffer=0x100250e8, size=6000)
627 err = ioctl(fd, SNDRV_PCM_IOCTL_WRITEI_FRAMES, &xferi);
I hit continue, and then it immediately stops at this function again. I can do
continue four more times and it does the same thing. On the sixth "continue",
there is an 8-second delay. Then my driver prints a message saying that it's
returning XRUN, and GDB stops again at snd_pcm_hw_writei(). I don't know what's
happening during that 8-second delay.
This whole process repeats forever.
Linux kernel developer at Freescale
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