UNIX 3.2 compatibility

[Rick Richardson]

In article <GKF29:xds13 at ficc.uu.net> peter at ficc.uu.net (Peter da Silva) writes:
>Some are, some aren't. For some reason ISC (and I think ESIX) uses a
>slightly different structure in /etc/conf, and a slightly different
>set of predefined system calls, than the Intel/AT&T baseline.

There doesn't appear to me to be any difference in the structure
of /etc/conf in ISC from the stock AT&T structure except for
the presence of the kconfig.d directory.  Our software, which
includes a couple of device drivers, comes in standard AT&T
ID format and installs and builds under ISC, AT&T, and SCO.

Note that you and any device driver packages that you install
can ignore what is in the kconfig.d directory under ISC UNIX if
you always use the AT&T idbuild (rather than ISC's kconfig) to
build new kernels.  A device driver that wants to be fully
compatible with either method of kernel build under ISC needs
to add a single line to the end of kconfig.d/description.

In fact, in my opinion, a 3.2 variant that is not downwards
compatible with the AT&T ID format isn't worth a dime.  I
only know of one system like this, which is 3.2 stuff Unisys
is selling.  To be fair, they have run time loadable drivers;
(something I was disappointed didn't make it into everybodies 3.2)
but they started and didn't finish the job of making them
coexist within the ID format.

The grey areas with drivers are with the internal driver support
functions.  You can depend on the standard ones that have been
around since V7.  But when you get into less well known areas,
each vendor diverges with their own 'invented here' method.
To have any chance of portability, a driver writer needing
these functions must use the ones that AT&T provides in their
3.2 and hope that the variant UNIX vendor hasn't deleted support
for that call.  We've been burned by this approach only recently,
again with Unisys (they apparently aren't found of 3rd party SW).

-Rick

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