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List:       alsa-devel
Subject:    [alsa-devel] CVS / OSS mixer emulation (important)
From:       Jaroslav Kysela <perex () suse ! cz>
Date:       2000-07-26 8:25:39
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Hello,

	anonymous CVS is up again. The mixer code in the lowlevel drivers
was ported (except Prodif Plus), but other parts require much more work
(OSS mixer emulation, alsa-lib, alsa-utils). I'll inform you about
additions.
	The code is highly unstable and I will not probably be able to
react on all bug reports in short time. Patches will be appreciated.

	The second part of this message is about OSS mixer emulation
layer (and perhaps OSS PCM emulation layer). Abramo has an idea to move
this emulation completely into the user space. We may use
/etc/ld.so.preload file to load the emulation code before any application
is executed and hack open(), close(), ioctl(), read(), write() and
mmap() functions.
	I see two problems here: 	

- preloaded emulation code may be big (if it is not possible to create
  only a simple and small wrapper) and each application will load this
  code even if it is not used
- static binaries are not able to use this code at all (it seems as not a
  big pain, bacause almost all binaries are dynamic current days)
- all software which uses preload scheme will not be able to use ALSA's
  OSS emulation (I think that esound and others use also this redirection)

Please, this issue is important for us at this time. We need to know the
decision for the OSS mixer emulation layer. The PCM emulation layer in the
user space will be probably always created, because we may use more tricks
for multichannel cards there and Abramo is waiting to show you, that even
Quake (mmap) is running with those hardware.

						Jaroslav

-----
Jaroslav Kysela <perex@suse.cz>
SuSE Linux    http://www.suse.com
ALSA project  http://www.alsa-project.org


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