At Fri, 13 Jun 2008 21:13:03 +0200, Lennart Poettering wrote:
Heya,
the HDA driver allows a playback buffer size of something like 64K onyl. Is this a driver limitation or a limitation of the hardware? Skimming through the docs I cannot see anything like this, and I got the idea that the audio buffer is maintained in system memory, not sound card memory, so why this limit?
This comes from the buffer pre-allocator. Run the below:
# echo 1024 > /proc/asound/card0/pcm0p/sub0/prealloc
then you can use now 1MB buffer. snd-hda-intel has max pre-allocation buffer size 1MB, and this is the hard-coded limit.
It's rather a silly constraint, and I think it'd be better cut off. OTOH, this makes the system safer (e.g. avoiding page allocations for too large buffers), and there is a proper workaround, too. So, I'm open about this change, so far.
Takashi