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. cheers, Kristian - 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
