> For sd, we gauge the size of the command from the > size of the medium: <1Gb=> six byte, from 1Gb to > 2Tb 10 byte, over 2Tb 16 byte By now this theory we have completely disavowed? I haven't seen our English yet mention that asking to read/write more than xFF blocks triggers us to skip past the commonly misunderstood x08/0A Read(6)/Write(6) standard of using x00 to mean x100. I think instead we resort immediately to x28/2A Read(10)/Write(10).
In http://lxr.linux.no/source/drivers/scsi/sd.c?v=2.5.56 I see fragments that match our later English: SRpnt->sr_device->ten = 1; if (block > 0xffffffff) { SCpnt->cmnd[0] += READ_16 - READ_6; ... if (((this_count > 0xff) || (block > 0x1fffff)) || SCpnt->device->ten) { ... SCpnt->cmnd[0] += READ_10 - READ_6; case ILLEGAL_REQUEST: if (SCpnt->device->ten == 1) { if (SCpnt->cmnd[0] == READ_10 || SCpnt->cmnd[0] == WRITE_10) SCpnt->device->ten = 0; } Being a dramatically raw Linux newbie, I can't know if sequencing this code to match the English is correct or not, nor indeed if I am reading the source file we mean. Click-thru ILLEGAL_REQUEST shows me three source files agree with me thinking by that jargon we mean x05. And more or less source files agree that by READ_6 READ_10 WRITE_10 we mean x 08 0A 2A. Cluelessly, curiously, thankfully yours, Pat LaVarre -----Original Message----- From: James Bottomley [mailto:[EMAIL PROTECTED] Sent: Mon 3/24/2003 9:56 AM To: Jens Axboe Cc: Linus Torvalds; Matthew Dharm; USB Developers; USB Storage List; Linux SCSI list Subject: [usb-storage] Re: PATCH: exclude certain commands from emulated SCSI hosts On Mon, 2003-03-24 at 10:52, Jens Axboe wrote: > It's not true, ->ten is set unconditionally and we only fall back to 6 > byte cdb's if we see an ILLEGAL_REQUEST on a READ_10/WRITE_10. > > So the logic is, always assume 10-byte commands. If an incoming request > cannot be addressed with 10-byte commands, use 16. Sorry, that was me misreading the fallback logic in sd.c Ten bytes it is unless we have problems. James _______________________________________________ usb-storage mailing list [EMAIL PROTECTED] http://www2.one-eyed-alien.net/mailman/listinfo/usb-storage N隊X'u)Y\gbH zG( )uޖX( ~zwNrz j_]jm?X( ~zwXb?)u
