On Fri, Jun 09 2006, Tejun Heo wrote: > zhao, forrest wrote: > >On Fri, 2006-06-09 at 12:47 +0900, Tejun Heo wrote: > >>If we're gonna do it. EH needs only a few changes probably during > >>autopsy and report. Fixing up command issue path and implementing > >>command exclusion (NCQ vs. non-NCQ, sil24 does it in hardware, ahci > >>doesn't) will be a bit complex though. > > > >Would you please elaborate on command exclusion? Why NCQ commands need > >to be excluded from non-NCQ commands? > > AHCI spec rev 1.1, sect 1.7. The last paragraph says. > > "This multiple-use of the command list is achieved by the HBA only > moving its command list pointer when the BSY, DRQ, and ERR bits are > cleared by the device. System software is responsible to ensure that > queued and non-queued commands are not mixed in the command list." This, btw, was also the case with the legacy TCQ. -- Jens Axboe - : send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
