michaelc@xxxxxxxxxxx wrote on Sat, 17 Mar 2007 18:13 -0500: > Pete Wyckoff wrote: > > dougg@xxxxxxxxxx wrote on Wed, 14 Mar 2007 12:18 -0400: > >> After reviewing this post by Pete Wyckoff: > >> http://marc.theaimsgroup.com/?l=linux-scsi&m=117278879816029&w=2 > >> > >> I decided to update my sg v4 interface document originally > >> posted 20061106 which I will now call release 1.1 : > >> http://lwn.net/Articles/208082/ > >> > >> Pete was proposing to put back din_iovec_count and > >> dout_iovec_count that had been dropped out of bsg but > >> had been in release 1.1 . Hmm. > >> > >> Some other items have been picked up from the bsg > >> implementation plus the suggestion from LSF'07 to > >> add dout_resid. > >> > >> See the attachment, comments welcome. > > > > Do you want to define the iovec format too? As I commented in my > > patch, v3 sg_iovec has pointers with 32/64-bit issues. Would be > > nice to see you declare v4 sg_iovec as pure u64. (By the way, don't > > use the patch: casting from the new to the old can put junk in the > > top half of the 64-bit sg_iovec.iov_len). > > > > Another issue I wonder about is queue DMA alignment. In bsg, > > blk_rq_map_user will use a bounce buffer if the user-supplied start > > and end addresses are not aligned. sg will happily map user pages > > at any offset without checking, although I haven't checked if Mike's > > patches change this. ll_rw_blk.c says regarding blk_rq_map_user: > > Currently and before any of my patches, sg checked the start > if (((unsigned long)hp->dxferp & > queue_dma_alignment(sdev->request_queue)) != 0) > It did not check the start and end like blk_rq_map_user. > > With my updated patches, blk_rq_map_user is just checking the start. > There was a thread about not checking the end on linux-scsi. I will try > to dig it up. A couple kernels ago the bio map helpers were modified to > only check the start. Oh, I missed that. There's this thread about USB needing end alignment too, on all but the last iovec entry: http://thread.gmane.org/gmane.linux.usb.devel/16230/focus=16409 -- Pete - 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
