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From: J Wunsch <j@uriah.heep.sax.de>
Message-Id: <199507301534.RAA15394@uriah.heep.sax.de>
Subject: Re: Update on my aic driver problems
To: gibbs@freefall.cdrom.com (Justin T. Gibbs)
Date: Sun, 30 Jul 1995 17:34:33 +0200 (MET DST)
Cc: joerg_wunsch@uriah.heep.sax.de, terry@cs.weber.edu,
        freebsd-current@freebsd.org, babb@freebsd.org
In-Reply-To: <199507301527.IAA12070@freefall.cdrom.com> from "Justin T. Gibbs" at Jul 30, 95 08:27:01 am
Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch)
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As Justin T. Gibbs wrote:
> 
> >> The 6260 doesn't support scatter/gather, I believe.

> >Hmm, well.  Scatter/gather is a required feature for FreeBSD, ain't
> >it?
> 
> No, its not.  What you'll have to do is allocate a 64k contiguous 
> staging buffer and do the transaction from there.  Since scatter/gather
> is handled at the controller driver layer, the rest of the SCSI system
> makes no assumptions about it use... it just happens that most transactions
> are to buffers that are not physically contiguous, so if you use DMA,
> you must have the staging buffer.  It should be possible to get it to
> work, but the performance won't be that great.

Oops.  The aic driver doesn't use DMA (it's in the TODO list at the
beginning of the file), so i'm not sure now: is this difference a
problem at all, or will i have to look elsewhere?

Is there any doc available on the Adaptec chips?

-- 
cheers, J"org

joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/
Never trust an operating system you don't have sources for. ;-)