Re: iSCSI : New PDU opcode usage in rev 5.92

[julian_satran@il.ibm.com]

Santosh,

On a given nexus the roles are static aren't they?

Julo

Santosh Rao <santoshr@cup.hp.com> on 19/04/2001 03:47:07

Please respond to Santosh Rao <santoshr@cup.hp.com>

To:   ips@ece.cmu.edu (ips)
cc:
Subject:  iSCSI : New PDU opcode usage in rev 5.92




Julian & All,

I've got a quick question on how the new opcode layouts would work for
dual mode scsi implementations. (i.e. initiators that responded in
target mode or targets that acted as initiators also).

The new opcode layout is :

----------------
X|I| | | | | | |
----------------
7 6 5 4 3 2 1 0

where bits 5-0 -> opcode
X -> retry bit
I -> immediate bit

The same values are used for the command as well as response opcodes and
bits X & I are intended to both be set to 1 by targets.

i.e. opcode for scsi command = scsi response = 0x01. the distinction b/n
command and response is based on targets setting X & I bits to 1.

Now, if an initiator [capable of target mode] sent the following
commands, how would they be interpreted :

1) 0xc4.
is this a text command being retried in immediate mode,
or is it a text response ?

2) 0xc1
is this a scsi command being retried in immediate mode,
or is it a scsi response ?

3) 0xc2
is this a scsi task mgmt command being retried in immediate mode,
or is it a scsi task mgmt response ?

etc.....

- Santosh

--
#################################
Santosh Rao
Software Design Engineer,
HP, Cupertino.
email : santoshr@cup.hp.com
Phone : 408-447-3751
#################################