Hi Martin/list:
I am trying to track down an issue I am seeing when trying to boot using
iSCSI root using the fastlinq qedi converged network adapter initiator
and an LIO target.
In this configuration, but using a non-LIO (hardware) iSCSI target,
everything "just works". But when I switch to using an LIO software
target, I get this error when booting:
2023-09-20T14:10:32.835358-0500 worker5 kernel: Illegally set Immediate Bit in iSCSI Initiator Scsi Command PDU.
... > 2023-09-20T14:10:32.835422-0500 worker5 kernel: Got unknown iSCSI
OpCode: 0x52
It looks like the fastlinq adapter is sending a SCSI write (0x12) with
the Immediate bit set (0x40).
The code in iscsi_target.c:iscsit_setup_scsi_cmd(): looks like this:
if (hdr->opcode & ISCSI_OP_IMMEDIATE) {
pr_err("Illegally set Immediate Bit in iSCSI Initiator"
" Scsi Command PDU.\n");
return iscsit_add_reject_cmd(cmd,
ISCSI_REASON_BOOKMARK_INVALID, buf);
}
But I looked at rfc3720, and it looks like SCSI PDUs can have the
Immediate Bit set:
10.3. SCSI Command
The format of the SCSI Command PDU is:
Byte/ 0 | 1 | 2 | 3 |
/ | | | |
|0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|
+---------------+---------------+---------------+---------------+
0|.|I| 0x01 |F|R|W|. .|ATTR | Reserved |
+---------------+---------------+---------------+---------------+
4|TotalAHSLength | DataSegmentLength |
+---------------+---------------+---------------+---------------+
8| Logical Unit Number (LUN) |
+ +
12| |
+---------------+---------------+---------------+---------------+
...
Where "I" is the immediate bit.
Frankly, I'm never sure I read the SPEC correctly, so I'm not sure if
I'm mistaken here, but it looks like LIO does not allow the Immediate
bit (and hence Immediate data), even though the SPEC does allow it. But
it also looks like, during negotiation phase, LIO negotiates
ImmediateData like any other parameter, allowing "YES".
In our testing, if we set ImmediateData=No in the target, then our
problem goes away, i.e. we can now boot from an LIO target. This is
because Immediate Data is negotiated off, of course.
Is this a bug, or is this adapter doing something wrong? I would
appreciate other viewpoints.
Thank you.
--
Lee Duncan
