On Tue, Jun 21, 2016 at 9:43 PM, Martin K. Petersen <martin.petersen@xxxxxxxxxx> wrote: >>>>>> "Shaun" == Shaun Tancheff <shaun@xxxxxxxxxxxx> writes: > > Shaun> SATA drives may support write same via SCT. This is useful for > Shaun> setting the drive contents to a specific pattern (0's). > > As indicated a while back, my preference would be for you to add support > for REPORT SUPPORTED OPERATION CODES. It's fine that you keep the RSOC > response simple and only list WRITE SAME(10/16). But I want to avoid > having different heuristics for libata's SCSI-ATA translation and for > hardware controller ditto. > > Shaun> If UNMAP is not set or TRIM is not available > > Please do not conflate the two. We have the appropriate fallbacks at the > block layer. It happens to be the same command descriptor but it is two > very different implementations at the device level. > > If the UNMAP bit is set you need to issue a DSM TRIM. If the device does > not support TRIM you need to return ILLEGAL REQUEST/INVALID FIELD IN > CDB. > > If the UNMAP bit is not set then it's a regular WRITE SAME and should be > issued using SCT WRITE SAME. If the device does not support SCT WRITE > SAME you need to return ILLEGAL REQUEST/INVALID FIELD IN CDB. Thanks for the clarification and the review. I will work on support for REPORT SUPPORTED OPERATION CODES and handle the WRITE SAME following the UNMAP as you described. Thanks! > -- > Martin K. Petersen Oracle Linux Engineering -- Shaun Tancheff -- To unsubscribe from this list: 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
