Date: Wed, 04 Jan 2006 18:54:48 +0100
Message-ID: <s5hsls398uv.wl%tiwai@suse.de>
From: Takashi Iwai <tiwai@suse.de>
To: mista.tapas@gmx.net
Cc: Adrian Bunk <bunk@stusta.de>, Jesper Juhl <jesper.juhl@gmail.com>,
       Olivier Galibert <galibert@pobox.com>,
       Alistair John Strachan <s0348365@sms.ed.ac.uk>,
       Jan Engelhardt <jengelh@linux01.gwdg.de>, Andi Kleen <ak@suse.de>,
       perex@suse.cz, alsa-devel@alsa-project.org, James@superbug.demon.co.uk,
       sailer@ife.ee.ethz.ch, linux-sound@vger.kernel.org, zab@zabbo.net,
       kyle@parisc-linux.org, parisc-linux@lists.parisc-linux.org,
       jgarzik@pobox.com, Thorsten Knabe <linux@thorsten-knabe.de>,
       zwane@commfireservices.com, zaitcev@yahoo.com,
       linux-kernel@vger.kernel.org
Subject: Re: [2.6 patch] schedule obsolete OSS drivers for removal
In-Reply-To: <20060104113726.3bd7a649@mango.fruits.de>
References: <s5h1wzpnjrx.wl%tiwai@suse.de>
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	<9a8748490601031256x916bddav794fecdcf263fb55@mail.gmail.com>
	<20060103215654.GH3831@stusta.de>
	<20060103221314.GB23175@irc.pl>
	<20060103231009.GI3831@stusta.de>
	<Pine.BSO.4.63.0601040048010.29027@rudy.mif.pg.gda.pl>
	<20060104000344.GJ3831@stusta.de>
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	<20060104113726.3bd7a649@mango.fruits.de>
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At Wed, 4 Jan 2006 11:37:26 +0100,
tapas wrote:
> 
> -- ALSA's default open mode is "blocking". But the ALSA API uses the
> term blocking in two meanings and throws them together into the open
> mode of a pcm device. Normally on device files, blocking access means a
> read()/write() returns, when there's data which has actually been
> read/written to the device. nonblocking access means, read()/write()
> return immediately. In ALSA blocking mode means above _plus_ that the
> open call will only immediately return (in case of contention) when the
> previous user of the audio device has given it up. 
> 
> The combination of the last two is deadly :) It leaves users with
> nonfunctional sound plus seemingly hanging apps when their soundcard is
> not hardware mixing capable. So IMHO, to fix these two issues really is
> the most pressing matter of all, but like i said, sadly ALSA devs seem
> to disagree (i haven't followed ALSA development that closely lately
> though).

Note that as of OSS emulation, this is no longer true.  The OSS
devices are opened as "non-blocking" per default.  ALSA native devices
are opened as "blocking" just to keep the compatible behavior,
though.


Takashi
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