Date: Thu, 9 Nov 2000 15:42:48 -0800 (PST) From: Matthew Jacob <mjacob@feral.com> To: "Justin T. Gibbs" <gibbs@scsiguy.com> Cc: "Kenneth D. Merry" <ken@kdm.org>, Wilko Bulte <wkb@freebie.demon.nl>, FreeBSD-alpha mailing list <freebsd-alpha@FreeBSD.ORG>, freebsd-gnats-submit@FreeBSD.ORG Subject: Re: alpha/22650: SCSI cdrom attach problems on 4-stable Message-ID: <Pine.BSF.4.21.0011091539140.46819-100000@beppo.feral.com> In-Reply-To: <200011092337.eA9Nbea96953@aslan.scsiguy.com>
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On Thu, 9 Nov 2000, Justin T. Gibbs wrote: > >> Since autosense is failing, the cd(4) driver can't tell what sort of error > >> is getting returned (and therefore whether the drive is really accessible), > >> so it won't attach. > > > >An AUTOSENSE failing means that a check condition occurred, but no sense data > >is available. That should, in fact, be treated identically to READ CAPACITY > >failing because there's no media. > > Are you saying that the Qlogic firmware will return autosense fail > if the sense information is all zeros (no sense)? That would be > really broken. No, no, no... It gives you a special status of "AUTOSENSE FAIL"- sort of much like how the AHA1542 does it. But you know a check condition occurred. > > >What's more important is that cam_periph_error or the periph should send a > >REQUEST SENSE if AUTOSENSE fails- the sim should not be the one doing this. > > I don't know that you are guaranteed to get correct sense in this case > as the first attempt to retrieve sense may have cleared or changed > the sense information. I do have this implemented, BTW, in some error > recovery enhancements I've made, but I still don't know that it is > the appropriate thing to do. Yes- that troubles me also. But w/o being able to say *why* autosense failed it's the best one can do. The pragmatics here are that if you have a CHECK CONDITION, maybe 7 times out of 10 you really don't care what the Sense Key is. It's either an operation you can retry on (most I/O to stateless devices) or fundamentally don't much care about (e.g., a CHECK CONDITION on a tape unload). -matt To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-alpha" in the body of the message
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