From: wcs@NeoSoft.com (Bill Simpson)
Subject: >PS/2 AIX article - horror story
Organization: NeoSoft Communications Services -- (713) 684-5900
Date: Fri, 09 Oct 1992 20:36:41 GMT
Keywords: IBM AIX DRIVER PS/2 RS/6000 

 <aknowles@expert.expert.com (Anne Knowles)> writes:
>I write for RS/Magazine, a magazine for RS/6000 users, and I am doing a story
>on PS/2 AIX. I would like to talk to any PS/2 AIX users out there about
>why they are using the operating system and, for users of both PS/2 AIX and
>AIX/6000, about the differences between the two. Please email me if
>you have any thoughts, comments, etc. Thanks in advance for any help.

I have a real horror story to tell! 

Dateline: Houston, TX, June 1990
    We know the RS/6000 is coming, but can't get one. We
    need to write a device driver for a special interface.
    IBM rep suggests we first write the driver on the PS/2
    under AIX ('the Microchannel busses are the same' NOT),
    and then a quick port to the RS/6000. So we do it.

Dateline: Houston, TX, July 1990
    We get an RS/6000 model 320. Guess what, no quick port.
    All the kernel services have changed (names - to protect
    the innocent I guess, and calling parameters). No hardcopy
    manuals are available, so we have to eek thru the 'info'
    system. The configuration system (methods, odm, etc...) is 
    totally new and unique. Anyway, we get through the port, and the
    DMA won't work (it did on the PS/2). Had to contact IBM
    in Finland to get any support, they finally found someone at
    IBM in Austin who knew that the MCA bus was different.
    The RS/6000 MCA does not support "slave DMA selection by I/O
    address (other than zero)", a common PS/2 mode. The board
    doesn't support any other mode (whoops!). Time to design a
    new board. Just because a MCA board works in a PS/2 doesn't
    mean it will work in the RS/6000.

Dateline: October 1990
    New board designed with Chips and Technology MCA bus interface
    chip that supports RS/6000 modes. But can't get production
    parts.

Dateline: January 1991
    Port the device driver to the new board. Big rewrite of
    the actual device driver, and major rewrite of configuration
    programs since the board architectures are so different.
    Finally, got it working.

Dateline: February 1992
    AIX 3.2 is out and our customers need it supported by our
    device driver. Recompile, install, and hard crash. Seems that
    the BUS_ID (the magic number that allows us to talk to the 
    MCA bus) was correct in the AIX3.1.x odm database, but wrong
    in AIX 3.2 and caused a hard kernel crash. Fixed that problem.

Dateline: September 1992
    RS/6000 model 220 is out with 'new and improved' MCA bus.
    High speed modes, etc. Guess what? Our driver works but
    at a snail pace! Some improvement. Turns out the 'DMA
    fairness enable' doesn't work, so turn it off and don't
    be fair, and everything works fine now. For how long?

PS/2 AIX and RS/6000 AIX are two different animals, and not
even remotely related!!! The best I can tell is that nobody
is running AIX on the PS/2. 
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Bill Simpson                         713/561-7797
Interface Consultants                713/561-0634 Fax
15326 Bonita Springs Drive           Internet: wcs@neosoft.com
Houston, TX 77083                    Compuserve: 76600,1577
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