[alsa-devel] hw_params function and OSS emulation

Timur Tabi timur at freescale.com
Thu Aug 23 20:43:40 CEST 2007

Takashi Iwai wrote:

> Err, usually, application = user-space application.  Do you mean
> really this?

Yes.  The application allocates a buffer, locks it down, and passes it to the 
kernel.  Since the buffer was allocated in user space, it is virtual 
contiguous but not physically contiguous, hence the need for a list of 
physical addresses.  To the hardware, the buffer appears as a collection of 
scattered buffers.  Hence, scatter/gather.

Like I said, I haven't look at the ALSA API for S/G, so I may be talking about 
an implementation of S/G that does not apply to ALSA.

Timur Tabi
Linux Kernel Developer @ Freescale

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