On 04/22/2009 12:23 PM, Jeff Garzik wrote: > Jeff Garzik wrote: >> Currently, libata creates a Scsi_Host per port. This was originally >> done to leverage SCSI's infrastructure to arbitrate among master/slave >> devices, but is not needed for most modern SATA controllers. And I >> _think_ it is not needed for master/slave if done properly, either. > > BTW note the above, with regards to the libata SCSI->block conversion. > libata currently relies on SCSI for some amount of generic device > arbitration, in several situations (see ->qc_defer, > SCSI_MLQUEUE_.*_BUSY). libata expects SCSI to be intelligent and not > starve devices, etc. > > >> I was able to successfully boot the following patch on >> AHCI/x86-64/Fedora. >> >> It may work with other controllers -- TRY AT YOUR OWN RISK. It will >> probably fail for master/slave configurations, and SAS & PMP also >> need looking at. It yielded this lsscsi output on my AHCI box: >> >> [0:0:0:0] disk ATA ST3500320AS SD15 /dev/sda >> [0:2:0:0] disk ATA G.SKILL 128GB SS 02.1 /dev/sdb >> [0:5:0:0] cd/dvd PIONEER BD-ROM BDC-202 1.04 /dev/sr0 > > For comparison, here is unmodified 2.6.30-rc3: > > [jgarzik@bd ~]$ lsscsi > [0:0:0:0] disk ATA ST3500320AS SD15 /dev/sda > [2:0:0:0] disk ATA G.SKILL 128GB SS 02.1 /dev/sdb > [5:0:0:0] cd/dvd PIONEER BD-ROM BDC-202 1.04 /dev/sr0 > Could the master/slave be simply solved by emulating a SCSI LUN for example below is my machine today: []$ lsscsi [0:0:0:0] disk ATA ST3160023A 3.01 /dev/sda [1:0:0:0] cd/dvd _NEC DVD_RW ND-3550A 1.05 /dev/sr0 [4:0:0:0] disk ATA WDC WD1600JS-60M 10.0 /dev/sdb the /dev/sda and /dev/sr0 share a master/slave wide cable (sdb is sata) it could be made to scan as: []$ lsscsi [0:0:0:0] disk ATA ST3160023A 3.01 /dev/sda [0:0:0:1] cd/dvd _NEC DVD_RW ND-3550A 1.05 /dev/sr0 [1:0:0:0] disk ATA WDC WD1600JS-60M 10.0 /dev/sdb So we need to emulate the REPORT_LUN (or what ever else) to return two LUNs. Or do you want to report a separate target for the master/slave? Thanks Boaz -- To unsubscribe from this list: 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
