On Wed, 2013-07-17 at 18:19 +0200, Alexander Gordeev wrote: > On Tue, Jul 16, 2013 at 02:38:03PM -0700, Nicholas A. Bellinger wrote: > > [ 7.927818] scsi_execute(): Calling blk_mq_free_request >>> > > [ 7.927826] scsi 0:0:0:0: Direct-Access ATA ST9500530NS CC03 PQ: 0 ANSI: 5 > > > > OK, so INQUIRY response payload is looking as expected here. > > Yep. It is not on the top of my head, but I remember something like INQUIRYs > are emulated and thus do not have payload. > > > [ 7.927960] sd 0:0:0:0: [sda] Sector size 0 reported, assuming 512. > > [ 7.927964] sd 0:0:0:0: [sda] 1 512-byte logical blocks: (512 B/512 B) > > [ 7.927965] sd 0:0:0:0: [sda] 0-byte physical blocks > > > > Strange.. READ_CAPACITY appears to be returning a payload as zeros..? > > Yep. Because blk_execute_rq() does not put the proper callback and data do > not get copied from sg's to bounce buffer. That is why I tried to use > blk_mq_execute_rq() instead. Once I do that, data start getting read and > booting stops elsewhere. Mmmmmm. The call to blk_queue_bounce() exists within blk_mq_make_request(), but AFAICT this should still be getting invoked regardless of if the struct request is dispatched into blk-mq via the modified blk_execute_rq() -> blk_execute_rq_nowait() -> blk_mq_insert_request() codepath, or directly via blk_mq_execute_rq().. Jens..? > > Of course, I was suspecting that change alone is not valid and wondered > about the status of scsi-mq in the first place, and if more changes are > coming. Most certainly. ;) > > So I it turns out "req->errors + req->resid_len" issue (you described > earlier) needs to be addressed before going forward with libata (only?). AFAICT, getting an initial conversion of libata up does not depend upon this specific issue being addressed first. I could be wrong however.. > > > Not sure why yet some control CDBs are getting back the expected > > payload, while others are returning zeros.. > > Bio buffers do not get updated from callback. > > > Also, looking at the included stack back-trace: > > [...] > > Thanks a lot for these and other your comments, Nicholas! > Sure. I should have a few extra cycles to hack on this over the weekend. Also, thinking about this some more, trying to convert ahci to scsi-mq first (using QEMU emulation), while keeping a rootfs on PIIX_IDE might make debugging slightly easier.. --nab -- 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
