[432] in linux-scsi channel archive
Project I'm working on, advice requested
daemon@ATHENA.MIT.EDU (JavaMan)
Thu Jul 27 20:34:36 1995
Date: Wed, 26 Jul 95 13:17:22 PDT
To: "Linux scsi hackers society" <linux-scsi@vger.rutgers.edu>
From: "JavaMan" <rolandd@swn.com>
Hi, In my "real job" I'm working on SCSI (and X.25, but that's not
important here) drivers and bootstrap code for the MVME167 platform
running LynxOS. We have two 167s in a rack, each has a secondary SCSI
controller on the other's primary SCSI bus. The secondary controller
only does SCSI-1 which means that to support multiple initiators we
must use SCSI reserve/release commands (tagged command queueing would
be faster and better, but only works for SCSI-2). I have a test
machine with a single bus that I'm using to modify the bootstrap code
to use reserve/release on the boot device. Here is where this becomes
Linux related, I want to use the Linux sg driver to send
reserve/release commands to the drive to test the robustness of the
Lynx boot code. For this, I need a ISA SCSI adapter which is settable
to SCSI ID #6, the '167 MB SCSI only works on ID 7 at least with
LynxOS. Adaptec informs me that the 152xA and 154xCF controllers both
are selectable to work off HA IDs other than 7. I have a couple of
questions relating to all of this. First, has anyone on the scsi list
used linux in an application similar to this who would be willing to
share their experience, pitfalls, etc? Next, will I have any problem
using the Adaptec 1522A controller jumpered to be HA ID 6?
(Performance is not an issue since I'm only using this controller to
do reserve/release testing.) Also, is it still the case that the
documentation for the sg interface is "read the source, luke"?
Finally, where would I look to try to disable the SCSI bus probe on
this controller? I have a feeling that Lynx may not work well with it
and I may have to disable it. I suppose I could boot linux while the
VME is sitting in it's ROM monitor to avoid any problems here if
necessary.
On another related issue, I heard that tagged command queueing had
recently been implemented for the Linux NCR53c{7,8}xx SCSI driver.
The MVME167 uses a NCR53c710 as it's controller, so this is very
interesting to me as we are looking at implementing tagged command
queueing as soon as we find a suitable second controller and have the
time to spend. Of course I couldn't use anything directly from the
Linux driver since it's GPL and LynxOS kernel is not, besides the fact
that the archetecture of the two platforms and operating systems is
rather different. I was hoping I might see some good hints on how to
(or how not to?) go about it.
Thanks in advance for any assistance/advice.
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