Sense fetching [Was: cdrtools /devel ...]
Joerg.Schilling at fokus.fraunhofer.de
Thu Nov 11 13:17:28 UTC 2010
Alexander Motin <mav at 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?
EMail:joerg at schily.isdn.cs.tu-berlin.de (home) Jörg Schilling D-13353 Berlin
js at cs.tu-berlin.de (uni)
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