Alan Stern wrote: > On Sat, 15 Oct 2005, Douglas Gilbert wrote: > > >>Alan, >>In include/scsi/scsi_eh.h there are several helper functions >>to aid processing SCSI errors. This includes SCSI sense data >>descriptor format (which won't be needed for DVD/HD/BD for >>some time with a (2**32 * 2048) byte maximum using existing >>fixed sense data format). However there is >>scsi_get_sense_info_fld() to fetch the info field. >> >>sd, st and sg have been converted to use these helpers, >>where appropriate. >> >>MMC-4 does not mention that the valid bit needs to >>be set on a MEDIUM/HARDWARE error and I have seen >>real life examples of this. [So it's poorly defined >>if one gets a medium error on lba 0.] You may also like to >>consider deferred errors which can occur according to >>MMC-4. > > > Thanks for the comments. It will be easiest to start with this patch and > then add others on top. I wouldn't mind writing another update to use > scsi_get_sense_info_fld and friends. > > I'm not familiar with the MMC standards and it will take some time to get > up to speed on MMC-4. I just downloaded the draft standard, and it's not > obvious where (if anywhere) it describes the sense data values. Alan, With mmc4r05a.pdf search for "medium error". It talks about setting the info field but says nothing about the valid bit. In similar situations sbc (disks) and ssc (tapes) do mention the valid bit. They should all conform to spc (primary commands) but at the margin (especially mmc) they don't. I have brought up the subject on the "t10@xxxxxxx" reflector, the response, if memory serves, was along the lines of "yep, live with it". > As for deferred errors, I don't know the proper way of handling them. It > would be better for someone else to take care of it. While searching in the pdf you could look for "deferred" as well. Lots of hits. Hard to say what exactly to do, but reporting something to the log wouldn't be a bad start. This file: include/scsi/scsi_dbg.h also contains sense data helper declarations. Aside ... not addressed to Alan Why this function is in scsi_dbg.h and is declared like this: extern const char *scsi_extd_sense_format( unsigned char, unsigned char); rather than something like this: extern const char *scsi_asc_ascq_str( unsigned char asc, unsigned char ascq); is beyond me. What has "_extd_" got to do with it? Basically even when I know the function is there, and publically available, it is still difficult to find! Doug Gilbert - : send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
