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Xref: sserve comp.unix.bsd:1821 comp.unix.internals:4898 Path: sserve!manuel!munnari.oz.au!mips!mips!sdd.hp.com!cs.utexas.edu!sun-barr!ames!agate!dog.ee.lbl.gov!horse.ee.lbl.gov!torek From: torek@horse.ee.lbl.gov (Chris Torek) Newsgroups: comp.unix.bsd,comp.unix.internals Subject: Re: Writing a device driver for CDROM Date: 2 Jul 1992 11:41:07 GMT Organization: Lawrence Berkeley Laboratory, Berkeley Lines: 28 Message-ID: <24317@dog.ee.lbl.gov> References: <1992Jun20.152106.159@rai.juice.or.jp> <24289@dog.ee.lbl.gov> <12sps1INNs18@rodan.UU.NET> Reply-To: torek@horse.ee.lbl.gov (Chris Torek) NNTP-Posting-Host: 128.3.112.15 Keywords: bsd devicedriver cdrom In article <24289@dog.ee.lbl.gov> I added, as an aside, >>Despite the sub-LUN stuff in the SCSI standards, I have never seen any >>SCSI units that in turn drive sub-units. Nonetheless, this particular >>scheme should handle them. In article <12sps1INNs18@rodan.UU.NET> lidl@rodan.UU.NET (Kurt J. Lidl) writes: >Well, all those people out there with sun3 shoebox drives have the >hardware necessary to do that. The Adaptec board in these boxes [maps] ... >scsi id 0, lun 0 -> /dev/rsd0 >scsi id 0, lun 1 -> /dev/rsd1 >scsi id 1, lun 0 -> /dev/rsd2 >scsi id 1, lun 1 -> /dev/rsd3 That is target + LUN, not target + LUN + sub-LUN. The SCSI subunits are done with message bytes, so that you get 256 subunits per unit. Since there are 8 possible units, this gives you as many as 2048 subunits per target (times 7 targets => 14336 total units). As there are SCSI codes reserved to printers and such, this sub-unit addressing is probably not intended for disks, but rather those things where you might actually *want* more than 8 `units' (SCSI serial ports, e.g.). My SCSI drivers should handle the Sun-3 shoebox drives (not, as Kurt pointed out, that you would *want* to use them, given a choice :-) ). -- In-Real-Life: Chris Torek, Lawrence Berkeley Lab CSE/EE (+1 510 486 5427) Berkeley, CA Domain: torek@ee.lbl.gov