Kristian Høgsberg wrote: > On 1/14/07, Stefan Richter <stefanr@xxxxxxxxxxxxxxxxx> wrote: >> On 14 Jan, James Bottomley wrote: >> > The block layer currently provides sector (512) byte alignment >> > guarantees. However, there has been talk in SCSI of reducing that to >> > word (4) since that's what most intelligent PCI controllers can cope >> > with. If you have any alignment constraints, they should be expressed >> > in the slave configure. >> >> OK, thanks. I will keep the explicit setting of the mask then. >> I actually think that everything should work just fine with 4 bytes >> alignment, but the SBP-2 spec mentiones 8 bytes alignment for the S/G >> tables. So maybe device firmwares will expect it that way even though >> IEEE 1394 doesn't impose such a restriction even on transfers with a >> payload of a multiple of 8 bytes. > > Do you have a reference to this 8 byte alignment requirement? I > couldn't find it browsing through the standard. Also, since the SBP-2 > driver has to convert the scatterlist to an SBP-2 page table, it can > just allocate the page table on a 8-byte boundary if that is required. > The entries in the scatter table have no alignment restrictions from > the SBP-2 side. > > By the way, is there a way to ask the SCSI stack to limit the size of > the entries in the scatterlist to 64k? This would greatly simplify > the conversion to SBP-2 page tables, since this is the maximum size > these can hold. > I think 64k is the limit already, but I think you can call blk_queue_max_segment_size in your scsi_host_template->slave_configure or slave_alloc to set the size to whatever you like. - 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
