On Fri, 2006-04-28 at 17:32 -0400, Jeff Garzik wrote: > If both host controller and device support 16-byte CDB, it should not be > limited to 12 bytes. Well, the limit should really only reflect what the controller supports. The SCSI heuristics, or slave configure flags should take care of the devices. > libata is not "playing games", just exporting what the hardware supports > as best the API allows. It needs to support 16-byte CDBs for the same > reason any SCSI LLDD supports 16-byte CDBs. I think he means this piece of code in libata-core.c:ata_dev_configure() ap->host->max_cmd_len = 0; for (i = 0; i < ATA_MAX_DEVICES; i++) ap->host->max_cmd_len = max_t(unsigned int, ap->host->max_cmd_len, ap->device[i].cdb_len); You're setting the max_cmd_len based on the largest one supported by the device. What happens if that's larger than the HBA can support? > Remember ATAPI<->SCSI bridges exist, thus any SCSI disk can appear > attached to ATAPI. Well, that's like attaching a 4TB SPI array to a qla1280 (which has a firmware 12 byte command limit). You don't do it unless you want a horrible mess. James - : send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
