[PATCH] Support large LUNs with SCSI2

From: Kurt Garloff (garloff@suse.de)
Date: Tue Feb 05 2002 - 15:00:11 EST

Hi Marcelo, Dave,

a change in Linux SCSI scanning code broke support for large LUNs on
EMC Symmetrix storage arrays.

The change was easy to identify, thanks to Doug Gilbert compiling a list of
recent SCSI changes. (THANKS, Doug!)
2.4.13:
  - [...]
  - don't probe luns > 7 for target <= SCSI_2

The new code is correct, AFAICT, so the EMC Symmetrix needs a special case.

I created a new BLIST_ flag for this, BLIST_LARGELUN.

When this flag is set, a device reporting as SCSI-2 will be treated as
SCSI-3 for the scanning code, which (at this moment) means that LUNs larger
than 7 are supported and the LUN bits in byte 2 of the CDB are not used for
the LUN addressing any more. (It's up to the host adapter that supports LUNs
> 7 to make sure the addressing is done appropriately.)

The patch has been tested and makes the high LUNs of the Symmetrix reappear.
No other devices are affected. (Though probably more of the SPARESLUN
devices are affected by the same problem and should be added this flag.)

Being at it, I also took time to finally document the BLIST_ flags in this
file, in order to make it more usable. Some comments were not at the right
position any more before.

Patch is against 2.4.18-pre8. Please apply.

Regards, 

-- 
Kurt Garloff                   <kurt@garloff.de>         [Eindhoven, NL]
Physics: Plasma simulations  <K.Garloff@Phys.TUE.NL>  [TU Eindhoven, NL]
Linux: SCSI, Security          <garloff@suse.de>    [SuSE Nuernberg, DE]
 (See mail header or public key servers for PGP2 and GPG public keys.)

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