[alsa-devel] Using speaker-test for sound cards which dont support mmap
Is it possible to use speaker-test for sound cards which do not support mmap? I straced speaker-test and it uses mmap call, can we bypass this?
Pharaoh . wrote:
Is it possible to use speaker-test for sound cards which do not support mmap?
If a sound card does not support DMA, the driver has to copy the samples from ALSA's buffer to the hardware with some other mechanism. However, there is always the ALSA buffer that can be mmap()ed to userspace.
_From the point of view of userspace applications, all sound cards support mmap.
Regards, Clemens
On Thu, 12 Jul 2007, Clemens Ladisch wrote:
From the point of view of userspace applications, all sound cards
support mmap.
It's not really true. Some drivers might not support mmap, but the mmap access can be partly "emulated" in alsa-lib using standard read/write mechanism.
Jaroslav
----- Jaroslav Kysela perex@suse.cz Linux Kernel Sound Maintainer ALSA Project, SUSE Labs
participants (3)
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Clemens Ladisch -
Jaroslav Kysela -
Pharaoh .