Date: Thu, 11 Nov 2010 14:17:21 +0100 From: Joerg.Schilling@fokus.fraunhofer.de (Joerg Schilling) To: mav@FreeBSD.org Cc: freebsd-scsi@FreeBSD.org, freebsd-current@FreeBSD.org, freebsd-stable@FreeBSD.org, marius@alchemy.franken.de Subject: Re: Sense fetching [Was: cdrtools /devel ...] Message-ID: <4cdbece1.EWYSqdvnx6XWF8EF%Joerg.Schilling@fokus.fraunhofer.de> In-Reply-To: <4CDBEA8B.1020306@FreeBSD.org> References: <4CD45209.5010607@FreeBSD.org> <20101105192028.GA68728@alchemy.franken.de> <4cd822df.o/wBtwsNCXiy8xZn%Joerg.Schilling@fokus.fraunhofer.de> <4CD82E2A.3070407@FreeBSD.org> <4cd8320a.U7/OjtLLBVtE4dTy%Joerg.Schilling@fokus.fraunhofer.de> <4CD83535.1010008@FreeBSD.org> <4cdbbfef.v4cr/k2jZr9gdpyF%Joerg.Schilling@fokus.fraunhofer.de> <4CDBC55B.1040307@FreeBSD.org> <4cdbc65f.bo%2BmYNFB2GPwXmq7%Joerg.Schilling@fokus.fraunhofer.de> <4CDBEA8B.1020306@FreeBSD.org>
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Alexander Motin <mav@FreeBSD.org> wrote:
> > Compare the number of sense bytes I like to request (18) with the number
> > previous FreeBSD versions did actually request. It is obvious that in case
> > there is a resid reported onm an old kernel, libscg (with your chanhge) would
> > believe that probably less that the absolute minumum of sense data is available.
>
> Kernel code I have changed affects only controllers without automatic
> sense fetching. For such controllers CAM previously always reported zero
> sense_resid, independently of requested size (which actually was also
> ignored in this case). So previously whatever you asked for 18 or 32
> bytes - sense_resid was always zero, like if you got full 18 or 32
> bytes. That was wrong. Now, in the same situation, if device wants to
> return let's say 20 bytes -- you will get 0 and 12 bytes of sense_resid
> respectively, meaning 18 and 20 bytes of received sense.
>
> AFAIK sense_resid always measured from the requested sense_len. In my
> patch for libscg you may see that I have changed both request and
> response paths. Resulted sense_count should be absolutely the same.
What is the requested size with the various HBAs in earlier kernels?
Jörg
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