IBM PS/2 SCSI Subsystem Linux Support
Content by Michael Lang (original archived HERE). Edited by Major Tom.
Last content update: 18 Sep 2003
This page contains the latest information about the development of the
IBM Micro Channel SCSI subsystem low level driver for Linux. See the subpages
for detailed description about this part of Linux.
Contents of These Pages
- 18 Sep 2003: A new driver release is in test. Several unexpected locks occurred.
- 11 Jan 2002: One year has passed and Kernel 2.5 is already deep in its development. Some changes have been applied to the driver in Kernel 2.5.
There are some modifications for the system locking. Please do not use Kernel 2.5.45 or previous releases of Kernel 2.5, as the SCSI driver won't work or
it will just run very slow. I am currently reshaping the driver and yes,
indeed, RAID support is still not out (sigh)...
- 18 Jan 2002: PSU replaced and model 8595 back on track. Thanks to everybody for your support and recommendations.
- 26 Dec 2001: Call for emergency support concerning broken power supply on model 8595-AK9 (see message above).
- 12 Sep 2001: Terrorism in USA - statement.
- 14 Jan 2001: Kernel 2.4.0 is now out for one week, including
driver version 4.0a, but it is not working correctly with the new kernel.
Yes, I am very sorry for that, but new technology never works on the first
stage... anyway, no excuses.
The new age defines things different, so it can happen, that the driver
is not called and/or none of your SCSI adapters gets detected!. The answer
to this is version 4.0b. This is located on the driver page here.
Model 80 problems with the SCSI driver are described in the FAQ of README.ibmmca.
- 4 Jan 2001: In order to better know, how the IBM MCA SCSI driver
is used and how much people really use it, it would be great, if every user
could just drop his usage data into the formular under Driver User Statistics. It is absolutely anonym, so no danger for you at all.
- 3 Jan 2001: The 4.0 drivercode was not working as a module.
This is solved by version 4.0a. Now it is working fine with kernel 2.4.x
and module support. In addition, some code got optimized. The knowledge,
applied in version 4.0a will soon appear also in 3.2d driver for older kernels.
But before this, the driverpage will be renovated or else you will not find
the right driver for your kernel anymore.
- 28 Dec 2000: Strange, I would bet, I placed some note here
still after 29 July... However, driver version 4.0 is released today. There
are from now on two drivers available for your support. People which still
use kernel older than 2.4.0 must use 3.xx drivers, while from kernel 2.4.0,
version 4.xx is required. You cannot do wrong. If you have the wrong driver
for your kernel release, the driver code stops the compilation of the kernel.
Major reasons for the new driver 4.0 were troubles with the interrupt handler
(my favourite bugsource) and with the DEVICE_INQUIRY command. These bugs
exist in 3.2, but they will be removed in 3.2c completely. See the history
section of README.ibmmca for latest changes.
- 29 Jul 2000: I took the last 10 days to finish minor work on
the 3.2 and the F/W support. So, today I hereby present
release 3.2 of the driver that is submitted
to the current kernel developments of 2.2, 2.3 and 2.4.
- 18 Jul 2000: The ANSI-device-order problem is now solved with
version 3.2pre9, just released on the driver-page. In addition, the possibility
that the IBM SCSI-2 F/W adapter could have an adapter PUN of 4-bit is now
taken into account, sticking strictly to the F/W manual.
- 17 Jul 2000: Warning! There could be a bug with the device access
in the PUN-mapping, when you have selected ANSI-device-order for mapping the
SCSI-devices! I hope to fix that during today. If you use standard device
order, you should not get any problems.
- 17 Jul 2000: 3.2pre8 is release today!
All reported problems
seem to be solved, now. Ghost-SCSI-interface on 9595 is now avoided by a
more restrictive check of the POS registers. In principal, if the driver
is not sure, if the device, shown in the integrated SCSI-POS is some
integrated SCSI-controller, it will be ignored. IBM SCSI F/W adapter support
is now working fine (autoprobing maximum synchronous transfer rate and
allowing wide-addressing (id=0..16)). COMMAND ERRORs, caused by overestimated
synchronous speed setting got corrected. Only dual-bus-mode to allow to
slow down speed on external SCSI-devices is not yet provided.
- 13 Jul 2000: Added a link to Louis Ohlands great MCA-page and
extended the latest README-file. The request for your POS registers in the
SCSI: line of the pos-file is no joke. I really need
that info from as much as possible people.
- 1 Jul 2000: Thanks to everybody who contributed hardware for
my test-setup. I have now the capabilities to test the driver on a broad
variety of PS/2 systems and types. This allows a much better bughunting than
- 4 Jun 2000: Back again from Italy and today I release
a new 3.2pre-release, that is 3.2pre7. This release behaves slightly
faster during I/O, because unused and complicated parts of the code got
deleted or optimized. A contribution from J. Shorney to activate the harddrive
activity LED on models 95A is added and common complaints by P. Hahn conerning
the various KERNEL_VERSION derivates is taken into account in this release.
To activate the harddrive LED on the model 95A in addition to the alphanumeric
LED panel, just use the commandline parameter activity now. Concerning
the bootproblems on various machines, we got THE big step ahead. I have some
(yet unofficial) patch here which modifies scsi_scan.c.
- 22 May 2000: Thomas Persson contributed a Bootdisk for S.u.S.E. 6.3
to install this Linux-distribution on MCA-machines. In addition, some links
were wrongly set on the driver-page. This got corrected now.
- 27 Apr 2000: Version 3.2pre1 got replaced by version 3.2pre2. The
reason was still a slight bug in the interrupt-handling of the driver, when
the PS/2 is cold-booted and the first device on the bus to be detected is
of sequential type, like tape-drives and kernel 2.2.x is used. In addition,
internal synchronous transfer at adapter maximum speed is guaranteed at
boottime. It is possible to slow down this synchronous rate for
troubleshooting (see README). The bug-report form WWW-page call for e-mail
this has been repaired and now your bug reports won't get swallowed by the
- 25 Apr 2000: Added some comments about supported hardware.
- 24 Apr 2000: Version 3.2pre1 of the driver is out! Please download it for testing and send bugreports to the
usual address. In addition, I provide missing ADF-files for your adapters
here. On the link-page, you may find (finally) a link to David Weinehall's
- 23 Apr 2000: Version 3.2 is now in test. Concerning E-Mail, you send
to me, I am sometimes burried in requests and questions, so please, if you
do not get any reply within one week, just send your E-Mail request again.
- 4 Apr 2000: Version 3.2 of the IBM SCSI-subsystem driver is coming
soon. It will contain the following optimizations:
- Better interrupt-handling for more watertight SCSI-command processing.
- Solution to the problem, why the driver reports errors, when everything
was obviously ok (hopefully).
- Recognition of commandline parameters in Kernel 2.3 and 2.4.
- 31 Oct 1999: Users having problems with the driver on boottime
and who have non-SCSI-II devices should try the kernel bootparameter
ibmmcascsi=bypass first. If the problem remains, please contact me.
- 28 Oct 1999: The tool scsiinfo as also kernel 2.3.23
cause a severe fatal kernel panic from the IBM SCSI-subsystem. It appears
some kind of sequencing error. If somebody can offer bugreports, they are
- 1 Oct 1999: I placed a new bootdisk for SuSE-distribution on the
bootdisk page. It has been provided by Peter Jakobsson. In any case, if you
think, you made a nice bootdisk for some Linux-distribution, please send it
to me. Requested bootdisks are for Debian and Redhat.
- 31 Aug 1999: Ok, today I was so happy, that I got positive feedback
from people using more than one IBM-SCSI-Adapter in their box. Regrettably,
there are still a lot of people out there who do not agree and receive heavy
problems with multiple IBM-SCSI-adapters! Please, if so, send me your problem-
and bug-report with details on your problem and when the system crashes. I
think that sometimes weired things do happen in multiple host mode.
- 1 Jul 1999: The release 3.1e of the SCSI-driver is included from
Kernel release 2.2.9.
- 18 Mar 1999: Test on the driver continues. By the way, IBM and
SAP now officially support the distribution and support for Linux customers,
users and developers. I already checked the developers support out on IBM,
and it worked! See this page for further info!
- 16 Mar 1999: Added a new page containing bootimages which come
up on IBM Micrcochannel machines with SCSI-adapters. It is all still under
- 3 Mar 1999: With version 3.1e, some problems with interrupt
handling can still appear, if you have more than one IBM
SCSI-subsystem. To get this under control, I am right now working on an
improvement in order to get it proof for multiple adapters. This will become
version 3.1f and should be ready within the next days.
- 23 Feb 1999: Even though, the latest driver-source has been
submitted to Linus, Kernel 2.2.2 contains still the 3.0f release.
I have again to warn everybody NOT(!!) to use 3.0f and to upgrade all
relevant files with the latest version from this server here. 3.0f will
not work on most PS/2 machines!
- 20 Feb 1999: Ok, I am careful with enthusiasm, but it seems, the
latest release of the driver is running on models 95XX, really. The latest
release is version 3.1e and it is offered on the driver-page. The reason for
the success is based on some unassigned variable memory for the SCBs, passed
to the SCSI-adapter. Since this bug in the implementation is solved, even
the problem with the Ooops-message, when looking inside /proc/mca has vanished.
Therefore, the ignorecmd and forgiveall is now obsolete!
Read the new README.ibmmca to be informed about the latest steps.
- 17 Feb 1999: Even though I found severe problems with the variable
handling in the driver, the version 3.1b does not yet appear to solve the
problems with 95XX series PS/2! Now, it shows a OOPS-message, really strange,
but do not give up hope, as I do not give up, either :-) !
- 15 Feb 1999: After some sequence of coincident events, I think,
I got the bug with models 95XX series solved!!! As I do not have one,
try the version 3.1b (is published on the page here
), and tell me about your results :-), but this time, I found really severe
reasons in the variable handling of the scb-structure, which was quite
- 13 Feb 1999: The problem, that still exists with some integrated
SCSI controllers seems to be limited to models of type 95XX. The 85XX
series should work with integrated SCSI-controllers. If somebody knows
about the technical differences in detail between the integrated
SCSI-subsystem on models 85XX and 95XX, feel free to send me some e-mail!
If you are owner of a model of type 95XX, where the integrated SCSI-driver
won't work with the linux driver, send e-mail to me with subject:
NOTIFY 95XX PROBLEM and an empty mail-body to me, so you will
be added to a list, and when the solution is found, you get immediate
e-mail in order to inform you about the problems' solution.
- 11 Feb 1999: Linux Kernel releases from 2.1.87 to 2.2.1 will
not work with
IBM SCSI-Adapter and the IBM SCSI-Adapter w/cache. If you
have a kernel version, lower than 2.2.2(!), get the latest ibmmca.c
SCSI-driver source file from this page! It will work with both types!