To: Marc Koschewski <marc@osknowledge.org>
Cc: Jan Engelhardt <jengelh@linux01.gwdg.de>, Phillip Susi <psusi@cfl.rr.com>,
       linux-kernel@vger.kernel.org
Subject: Re: CD-blanking leads to machine freeze with current -git
References: <58cb370e0601270837h61ac2b03uee84c0fa9a92bc28@mail.gmail.com>
	<20060210175848.GA5533@stiffy.osknowledge.org>
	<43ECE734.5010907@cfl.rr.com>
	<20060210210006.GA5585@stiffy.osknowledge.org>
	<43ED04E9.9040900@cfl.rr.com>
	<Pine.LNX.4.61.0602111614050.17942@yvahk01.tjqt.qr>
	<20060211152518.GB5721@stiffy.osknowledge.org>
From: Doug McNaught <doug@mcnaught.org>
Date: Sat, 11 Feb 2006 10:35:19 -0500
In-Reply-To: <20060211152518.GB5721@stiffy.osknowledge.org> (Marc
 Koschewski's message of "Sat, 11 Feb 2006 16:25:18 +0100")
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Marc Koschewski <marc@osknowledge.org> writes:

> The cdrecord man page says this:
>
> 	Setting the -immed flag will request the command to return
> 	immediately while the operation proceeds in background, making
> 	the bus usable for the other devices and avoiding the system
> 	freeze.  This is an experimental feature which may work or
> 	not, depending on the model of the CD/DVD writer.  A correct
> 	solution would be to set up a correct cabling but there seem
> 	to be notebooks around that have been set up the wrong way by
> 	the manufacturer.  As it is impossible to fix this problem in
> 	notebooks, the -immed option has been added.

> It how can the bus run the command sent on the device 'in the
>background' when it can only process _one_ request at a time?
>
> To me it sound like the foreground process (cdrecord) fork()s a
>process to blank the CD-RW. Clear. But you said the bus is not able
>to do so... I'm not getting this.

Some CD writers are apparently able to release the bus while
blanking, allowing use of the bus by other devices.  The 'immed' flag
tries to use this feature.  fork() has nothing to do with it--he's
talking about the IDE command, not the cdrecord program.

-Doug
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