Chipset autodetect -- pro and con

John Foster john at tsf.net
Mon Nov 30 08:23:18 CET 1998


A couple of ideas to consider - single all inclusive chipset support vs.
modularized chipset specific builds:
1. The bios core is relatively stable
2. Chipsets keep changing
3. CPU platforms change over time - 386, 486, ........
4. There are usually 2 or 3 places in the code where chipset initialization
is called - usually very early in the code
5. Encountered these problems in the 16 bit bios over many iterations,
finally arrived at a basic structure that
included a chipset module.  The chipset modules required some ASM and some C
and some H code. Rather than
create 3 files for a chipset, I created one file to keep the chipset info in
a convenient place and then extracted the ASM,C, and H info
into 3 temporary files when doing the build.
6. Did this about ten years ago using MS C and MASM - primitive but it works
7. MS H2INC utility is very nice - lets one use one H definition file for
both C and MASM structures so they are always in sync with each other
8. A bios build was based on a configuration file (xxx.job) that defined
variables for the build for a particular configuration
9. Separating the chipsets from the core code made it easier to debug
developing new chipset code and to update core code - by allowing testing to
verify core code on existing platforms
10. It also made creating new chipset code easier because it is all defined
in one separate file.

 BTW - the openbios.org domain has a temporary link to M's new pages - a bit
of kludge so far - but we will work on getting this prettified and organized
:-)

John






-----Original Message-----
From: M Carling <m at midgard.net>
To: openbios at elvis.informatik.uni-freiburg.de
<openbios at elvis.informatik.uni-freiburg.de>
Date: Sunday, November 29, 1998 9:13 PM
Subject: Chipset autodetect -- pro and con


>
>
>There seems to be some disagreement over the issue of whether or not
>OpenBIOS should provide for possibility to compile into a single binary
>support for multiple chipset types to be autodetected at run-time.
>
>For OpenBIOS to be successful, it needs to become more attractive to
>the MB manufacturers than the alternatives. I don't know whether such
>a feature would be attractive to the MB manufacturers or not. I suggest
>will begin by compiling a list of the advantages and disadvantages of
>this feature. Having done that (so that we understand it ourselves as
>best we can) we should then ask the manufacturers. (This will be a good
>step toward getting free hardware from them for development.)
>
>When we ask them, we should also ask any other questions about their
>needs. In effect, we need to do some market research.
>
>Here are the advantages and disadvantages that I can think of. There are
>probably others.
>
>Pro:
>
>It's cool.
>
>It would allow manufacturers to have one BIOS ROM that supports all
>their MB products.
>
>The autodetect code might also be useful for diagnostics.
>
>Con:
>
>Extra complexity--something else to go wrong. Bug free code is *really*
>important in the BIOS.
>
>Extra complexity--more difficult to test.
>
>What other questions would we like the MB manufacturers to answer for us?
>
>M



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