On Mon, 2011-01-17 at 18:18 +0100, Tejun Heo wrote: > Hello, James. > > On Mon, Jan 17, 2011 at 10:18:51AM -0600, James Bottomley wrote: > > > The problem is that the PMP device itself is currently not allocated a > > > userland visible device, so it doesn't have any /dev/* node. Hmmm... > > > > So perhaps it should be. If you look at the equivalent topology on SAS, > > our expanders have a bsg device node precisely so that we can do this. > > > > That said, SAS expanders have a defined protocol (SAS Management > > Protocol) to talk to the outside world, so they are real visible objects > > always in our topology ... I'm not sure PMP has this ... it seems that > > all PMP visibility is an extension to the standard? > > SATA PMP is mostly a dumb switch and there isn't much which can be > done by issuing custom commands (and IIRC we didn't have bsg back > then), so it was never made visible to userland, but yeah probably > exporting a bsg node is a good idea. Inside libata, the PMP device > has its device representation and all so it shouldn't be too difficult > either. Not really sure how the inquiry and stuff should be handled > tho. Expanders aren't SCSI devices either ... that means they don't appear as visible to standard SCSI mechanisms like INQUIRY (SMP isn't a SCSI protocol it's a SAS extension). They just appear as part of the topology in the device tree. James -- 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
