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Date: Wed, 21 Jun 2006 11:10:33 +0200
From: Andreas Mohr <andim2@users.sourceforge.net>
To: Andrew Morton <akpm@osdl.org>
Cc: linux-kernel@vger.kernel.org, hal@lists.freedesktop.org, gregkh@suse.de,
       linux-usb-devel@lists.sourceforge.net
Subject: Re: USB/hal: USB open() broken? (USB CD burner underruns, USB HDD hard resets)
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Hi,

On Tue, Jun 20, 2006 at 01:37:41AM -0700, Andrew Morton wrote:
> On Mon, 19 Jun 2006 10:21:54 +0200
> Andreas Mohr <andi@rhlx01.fht-esslingen.de> wrote:
> 
> > I'm having severe issues with cdrecord aborting with "buffer underrun"
> > message, *always*. Problem nailed, see below.
> 
> [hald polling causes cdrecord to go bad on a USB CD drive]
> 
> One possible reason is that we're shooting down the device's pagecache by
> accident as a result of hald activity.  This shouldn't happen, but still.
> Could you please do
> 
> `watch -n1 cat /proc/meminfo' and/or `vmstat 1'
> 
> then run cdrecord
> 
> then wait a bit
> 
> then run hald, see if the amount of pagecache (/proc/meminfo:Buffers or
> /proc/meminfo:Cached) suddenly decreases.
> 
> If the answer is "no" then I guess there's some unpleasant interaction
> happening at the USB level

"no":
both values don't show any noticeable decrease whatsoever upon a second
parallel open() of the device which makes burning abort.

It seems to be a USB thingy, as I will show in my next mail.

Andreas Mohr