Date: Wed, 30 Mar 2011 17:32:53 +1100 From: Lawrence Stewart <lstewart@freebsd.org> To: Alexander Motin <mav@freebsd.org> Cc: Brandon Gooch <jamesbrandongooch@gmail.com>, freebsd-scsi@freebsd.org, FreeBSD-Current <freebsd-current@freebsd.org>, FreeBSD Stable <freebsd-stable@freebsd.org> Subject: Re: Sense fetching [Was: cdrtools /devel ...] Message-ID: <4D92CE95.7040505@freebsd.org> In-Reply-To: <4CDE5B8C.4000102@FreeBSD.org> References: <4CD45209.5010607@FreeBSD.org> <AANLkTik5gBjUo3Qxs6rtgZMo8fnDFaSN-X3qEjRzB=QQ@mail.gmail.com> <4CDE5B8C.4000102@FreeBSD.org>
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On 11/13/10 20:34, Alexander Motin wrote: > Brandon Gooch wrote: >> 2010/11/5 Alexander Motin <mav@freebsd.org>: >>> Hi. >>> >>> I've reviewed tests that scgcheck does to SCSI subsystem. It shown >>> combination of several issues in both CAM, ahci(4) and cdrtools itself. >>> Several small patches allow us to pass most of that tests: >>> http://people.freebsd.org/~mav/sense/ >>> >>> ahci_resid.patch: Add support for reporting residual length on data >>> underrun. SCSI commands often returns results shorter then expected. >>> Returned value allows application to know/check how much data it really >>> has. It is also important for sense fetching, as ATAPI and USB devices >>> return sense as data in response to REQUEST_SENSE command. >>> >>> sense_resid.patch: When manually requesting sense data (ATAPI or USB), >>> request only as much data as user requested (not the fixed structure >>> size), and return respective sense residual length. >>> >>> pass_autosence.patch: Unless CAM_DIS_AUTOSENSE is set, always fetch >>> sense if not done by SIM, independently of CAM_PASS_ERR_RECOVER. As soon >>> as device freeze released before returning to user-level, user-level >>> application by definition can't reliably fetch sense data if some other >>> application (like hald) tries to access device same time. >>> >>> cdrtools.patch: Make libscg (part of cdrtools) on FreeBSD to submit >>> wanted sense length to CAM and do not clear sense return buffer. It is >>> mostly cosmetics, important probably only for scgcheck. >>> >>> Testers and reviewers welcome. I am especially interested in opinion >>> about pass_autosence.patch -- may be we should lower sense fetching even >>> deeper, to make it work for all cam_periph_runccb() consumers. >> >> Hey mav, sorry to chime in after so long here, but have some of these >> patches been committed (as of r215179)? >> >> Which patches are still applicable for testing? I assume the cdrtools >> patch for sure... > > Now uncommitted pass_autosence.patch and possibly cdrtools.patch. > To add another data point, I just applied the pass_autosence.patch to my ahci enabled 8.2-STABLE r220153 kernel and I can now burn successfully with cdrecord. The same kernel without the patch was unable to burn (though it could erase disks ok). Cheers, Lawrence
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