Re: ALSA on AMD64 with a 32-bit userspace

[Takashi Iwai <tiwai@suse.de>]

Hi,

thanks for the patches.

At Fri, 22 Apr 2005 11:04:53 +0200,
István Váradi wrote:
> 
> Hi,
> 
> I am using ALSA with a 64-bit AMD64 kernel (2.6.11) but with 32-bit
> applications. While trying to use Rosegarden4 (with JACK and
> Fluidsynth), I encountered some problems:
> 
> - some sequencer-related ioctl's did not work correctly because the
> kernel member of seq_port_info structure was not initialized. I
> attached a patch that initializes this to 0.

Note that the 32bit-compat ioctl framework was majorly rewritten in
the recent kernel, but this is still true for the old code remaining
in alsa-driver tree.

> - start the playback with snd_pcm_hw_start failed with -EPIPE, because
> some pointers were not updated. I attached a patch for alsa-lib 1.0.8,
> in which sync_ptr is called before SNDRV_PCM_IOCTL_START. It seems to
> solve the problem, though I don't know alsa-lib enough to be sure that
> this is the right solution...

Your fix should be OK.  It's harmless for non sync-ptr case, anyway.

Both are applied to CVS now.


> With these patches playback works, but JACK always reports xruns,
> whereas there aren't any. I discovered that the xruns are detected in
> the alsa_driver_wait function in alsa_driver.c (in JACK) returns 0,
> because the snd_pcm_avail_update calls in that function return 0.
> Putting sync_ptr into snd_pcm_avail_update does not seem to solve the
> problem.

Hmm, strange.  Anyway, sync_ptr() is already there in
snd_pcm_hw_avail_update() in the alsa-lib CVS version.  So, it should
be sync'ed before calculation of avail size.


Takashi


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