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List:       packet-writing
Subject:    Re: Problems with Yamaha CDR4416S and AHA1542
From:       Peter Osterlund <petero2 () telia ! com>
Date:       2002-05-06 21:14:39
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On Mon, 6 May 2002, Jens Axboe wrote:

> On Sun, May 05 2002, Peter Osterlund wrote:
> > On Wed, 13 Mar 2002, Jens Axboe wrote:
> > 
> > > On Wed, Mar 13 2002, Manfred Kreisl wrote:
> > > > Hi,
> > > > 
> > > > I can make packet-writing work.
> > > 
> > > I suppose that should rean "can't" :-)
> > > 
> > > The problem is that you have the your CD-RW on the 1542 adapter. That
> > > only supports 16 segments in a request, packet writing typically needs
> > > 32.
> > 
> > This is now supported in the 2.5 version of the packet patch:
> > 
> > http://w1.894.telia.com/~u89404340/patches/packet/2.5/packet-2.5.13.patch.bz2
> > 
> > There is a new config option which when enabled makes sure to use 4kb
> > segments, which means that 16 segments is enough for a 64kb packet.
> 
> I disagree with making this an explicit option, it would be far better
> to find the host the particular device is on and check for scatter
> gather limits. It's all right there in the request queue (hint:
> nr_phys_segments)

Thanks for the hint. The 2.5.14 patch implements your suggestion:

http://w1.894.telia.com/~u89404340/patches/packet/2.5/packet-2.5.14.patch.bz2

-- 
Peter Osterlund - petero2@telia.com
http://w1.894.telia.com/~u89404340


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