* Using speaker-test for sound cards which dont support mmap
@ 2007-07-11 16:40 Pharaoh .
2007-07-12 7:08 ` Clemens Ladisch
0 siblings, 1 reply; 3+ messages in thread
From: Pharaoh . @ 2007-07-11 16:40 UTC (permalink / raw)
To: alsa-devel
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?
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Using speaker-test for sound cards which dont support mmap
2007-07-11 16:40 Using speaker-test for sound cards which dont support mmap Pharaoh .
@ 2007-07-12 7:08 ` Clemens Ladisch
2007-07-12 7:13 ` Jaroslav Kysela
0 siblings, 1 reply; 3+ messages in thread
From: Clemens Ladisch @ 2007-07-12 7:08 UTC (permalink / raw)
To: Pharaoh ., alsa-devel
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
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Using speaker-test for sound cards which dont support mmap
2007-07-12 7:08 ` Clemens Ladisch
@ 2007-07-12 7:13 ` Jaroslav Kysela
0 siblings, 0 replies; 3+ messages in thread
From: Jaroslav Kysela @ 2007-07-12 7:13 UTC (permalink / raw)
To: Clemens Ladisch; +Cc: Pharaoh ., alsa-devel
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
^ permalink raw reply [flat|nested] 3+ messages in thread
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2007-07-11 16:40 Using speaker-test for sound cards which dont support mmap Pharaoh .
2007-07-12 7:08 ` Clemens Ladisch
2007-07-12 7:13 ` Jaroslav Kysela
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