* How does ALSALIB commuciates with low level kernel API
@ 2016-06-14 23:12 Chemsi Mehdi
2016-06-15 7:00 ` Clemens Ladisch
2016-06-20 17:43 ` Vinod Koul
0 siblings, 2 replies; 3+ messages in thread
From: Chemsi Mehdi @ 2016-06-14 23:12 UTC (permalink / raw)
To: alsa-devel
Dear experts,
I am too new in ALSA, trying to read a little bit and understand.
I want to underatnd how ALSA userspace API calls kernel space code ?
for example when I call snd_pcm_open() which code is called in kernel
sound code ?
and how the link is made ? via IOCTL/write ?
Please clarify
Thanks a lot in advance.
Mehdi
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: How does ALSALIB commuciates with low level kernel API
2016-06-14 23:12 How does ALSALIB commuciates with low level kernel API Chemsi Mehdi
@ 2016-06-15 7:00 ` Clemens Ladisch
2016-06-20 17:43 ` Vinod Koul
1 sibling, 0 replies; 3+ messages in thread
From: Clemens Ladisch @ 2016-06-15 7:00 UTC (permalink / raw)
To: Chemsi Mehdi, alsa-devel
Chemsi Mehdi wrote:
> I want to underatnd how ALSA userspace API calls kernel space code ?
> for example when I call snd_pcm_open() which code is called in kernel
> sound code ?
The generic PCM code in alsa-lib/src/pcm/pcm.c calls some plugin.
The "hw" plugin (in pcm_hw.c) handles communication with the kernel.
The kernel code is in sound/core/.
> and how the link is made ? via IOCTL/write ?
Yes.
Regards,
Clemens
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: How does ALSALIB commuciates with low level kernel API
2016-06-14 23:12 How does ALSALIB commuciates with low level kernel API Chemsi Mehdi
2016-06-15 7:00 ` Clemens Ladisch
@ 2016-06-20 17:43 ` Vinod Koul
1 sibling, 0 replies; 3+ messages in thread
From: Vinod Koul @ 2016-06-20 17:43 UTC (permalink / raw)
To: Chemsi Mehdi; +Cc: alsa-devel
On Wed, Jun 15, 2016 at 12:12:24AM +0100, Chemsi Mehdi wrote:
> Dear experts,
>
> I am too new in ALSA, trying to read a little bit and understand.
> I want to underatnd how ALSA userspace API calls kernel space code ?
> for example when I call snd_pcm_open() which code is called in kernel
> sound code ?
easist would be to start gdb on alsa-lib snd_pcm_open() and start tracing
the steps.
> and how the link is made ? via IOCTL/write ?
IOCTL, see sound/core/pcm_native.c on kernel side..
--
~Vinod
^ permalink raw reply [flat|nested] 3+ messages in thread
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2016-06-14 23:12 How does ALSALIB commuciates with low level kernel API Chemsi Mehdi
2016-06-15 7:00 ` Clemens Ladisch
2016-06-20 17:43 ` Vinod Koul
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