Sergei Steshenko wrote:
> I might be wrong, but it seems that 4096 bytes limit comes from these
> facts:
> 
> 1) on Linux page size is 4096 bytes;
> 2) if one allocate more than 4096 bytes, the system cannot guarantee the
> pages are contiguous;
> 3) ALSA uses DMA whenever the card supports it;
> 4) DMA needs contiguous buffer, so we are back to one page 4096 bytes
> buffer.

It's a windows application running through wine. This app uses dsound 
and I configured wine to use the alsa driver.

If we're at it, can I snd_pcm_mmap_begin()/commit() more than 4096 
bytes? It seems as at it's possible since wine's alsa driver does that 
on the whole buffer, which can be more than 4096 bytes. Does the alsa 
driver allocate DMA memory in that case?

tom

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