On Apr. 15, 2008, 16:38 +0300, Boaz Harrosh <bharrosh@xxxxxxxxxxx> wrote: > On Tue, Apr 15 2008 at 16:08 +0300, James Smart <James.Smart@xxxxxxxxxx> wrote: >> Boaz Harrosh wrote: >>> Let through up to the largest command of 260 defined by the scsi standard. >>> iscsi core supports this already. Now that the scsi-ml supports it we can >>> start using large commands. >> Just to double-check: >> if we use sg_io to pass through requests from user-land, which are addressed to >> drivers or transports, and which may not be a SCSI command but rather just something >> utilizing the sg_io infrastructure for management or pass-thru, are we limited to >> 260 bytes for request/cmd payload ? >> >> -- james s > > I think that only bsg, after the pending patches get accepted, will let you > pass larger then 16 bytes commands from user-land. sg_io is I think limited > to 16. However this could be fixed. (With sg_io, did you mean commands going > through the sg.c driver?) > > The block layer imposes no limits, and so is scsi-ml. The only limits are from > ULDs, and LLDs, like here, iscsi protocol does not support more then > SCSI_MAX_VARLEN_CDB_SIZE (260). Actually the 260 byte limit comes from SCSI variable length CDB maximum length. iSCSI allows to send larger CDBs with the Extended CDB AHS that has a 16 bit length field. Within the protocol constraints, the longest CDB would be 16 (in BHS) + 65532 (in AHS) = 65548 bytes long :) Benny > > If you need support in any other ULD, I will be happy to help. > > Boaz > > -- > 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 -- 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
