Moore, Eric Dean wrote: > On Wednesday, October 19, 2005 3:00 PM, Luben Tuikov wrote: > > >>On 10/19/05 16:08, Moore, Eric Dean wrote: <snip> > Luben suggestion(correct me if I'm wrong) is this should be > done thru user space, instead of exporting this in the > /sys/class/sas_phy attributes. Thus we need to export a > SMP_PASSTHRU mechanism. I believe there is discussion > by Christoph ( and I believe Luben backs this idea) of doing > all this thru the /dev/sg interface. Folks, Just a suggestion if you want to bring /dev/sg into the picture for a SMP (and even a STP) passthrough. The host could define a lun (pick a number) and the LLDD could supply the target code for it (as scsi_debug does for example). Details need to be sorted out (e.g. pdt of "host" lun) and a way to pass an 8 byte SAS address through a SCSI cdb (there are lots of vendor specific SCSI opcodes available). For a STP pass through, we have the SAT ATA PASS THROUGH SCSI commands already defined (although they don't allow for an 8 byte target (SAS) address). SG_IO code paths through the SCSI subsystem are pretty well tested and are available in all lk 2.4 and 2.6 kernels. All OSes that I am aware of have some sort of SCSI pass through mechanism so this approach bypasses the objection to adding new ioctls (from both Microsoft and Linux). The idea is not original. Windows 2000 has a lun for just this purpose (and it was dropped in Windows 2003). 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
