Sense fetching [Was: cdrtools /devel ...]
Joerg.Schilling at fokus.fraunhofer.de
Thu Nov 11 10:33:07 UTC 2010
Alexander Motin <mav at FreeBSD.org> wrote:
> > The question still remains whether the previous implementation did return resid
> >> 0 in some cases. In this case, I would need to implement both variants in the
> > libscg adaption layer and I would need to know whether I am running on an old
> > version or on a new version kernel. Do you know of a simple method to implement
> > this distinction?
> Yes, some drivers were permanently reporting zero resid, while others
> (mostly real SCSI) were reporting proper values. Now it is the same,
> just more cases should work properly.
> Why do you want/need to distinguish them? You should already handle
> non-zero resid properly. Zero resid may be wrong in some cases, but at
> first I don't see fatal problem from it and at second I don't see what
> can you do about it.
> If I am missing something - sorry, explain it to me please.
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.
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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