2001-10-29 19:57:29

by Khalid Aziz

[permalink] [raw]
Subject: To SCSI driver maintainers: 16-byte CDB support in SCSI interface drivers

ac series kernels starting with 2.4.10-ac5 contain a patch that enables
SCSI midlayer to send SCSI commands larger than 12 bytes to the
interface
drivers. Before sending a larger command, midlayer will check the
command size against Scsi_Host->max_cmd_len. If Scsi_Host->max_cmd_len
is larger than or equal to the command size, the command will be sent
to the interface driver else it will be terminated with an error.
scsi_register() sets Scsi_Host->max_cmd_len to 12 by default for every
interface. If a driver and the interface can support larger commands,
the driver should set Scsi_Host->max_cmd_len to the correct value after
calling scsi_register(). Please make this change to your driver if you
would like to support larger SCSI commands. Non-ac kernels will not
be affected by this change since Scsi_Host->max_cmd_len is unused on
those kernels.

--
Khalid

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Khalid Aziz Linux Systems Operation R&D
(970)898-9214 Hewlett-Packard
[email protected] Fort Collins, CO