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SubjectRe: UDI and Politics (was Re: Linux, UDI and SCO.)
   Date: 	Sat, 19 Sep 1998 15:12:55 -0500 (CDT)
From: "Edward S. Marshall" <>

I think this is something this discussion has been seriously missing;
input from some of those who really will be deciding this:

- Linus Torvalds and other kernel developers (Alan's been involved a bit,

Well, not that anything I saw is official in any way, but I've been
keeping quite because I've been amazed how stupid most of the UDI
discussion has been.

Let's back off and have a fresh perspective on things.

First of all, from looking at the UDI spec, UDI drivers will likely not
be as performant as "native" drivers. So there will still be incentives
for people who want device drivers for Linux to actually go and write
them, and for those people to pester manufactuers for specifications.
(Or reverse-engineer or disassemble the UDI driver for programming
information. :-)

Secondly, UDI drivers will almost certainly be loadable kernel modules,
using a fixed, and well defined interface. Linus (as the main copyright
holder of the Linux kernel) has already said that loadable kernel
modules which restrict themselves to the kernel interface as defined by
/proc/ksyms are considered separate entities, and are not covered by the
GPL copyright --- just as user programs which use the normal kernel
system calls are not considered part of the kernel, but using normal
kernel services. So all of the copyright arguments are also a red

Furthermore, what do you think the APM code in the Linux kernel does?
It makes calls to the APM BIOS! Or the Linux Bootstrap code, which
makes calls to the system BIOS. The System BIOS and the APM BIOS are
not GPL'ed on most systems --- indeed, source code is usually not
available in any form. Why is this not a problem?

Well, let's think about it. The System BIOS and APM BIOS have a
well-defined, and standardized interface. When you buy a computer, it
comes with BIOS installed on ROM's as a matter of course. So the fact
that the System BIOS and the APM BIOS are not free doesn't get people's
way, and they probably simply don't think about it.

Similarly, suppose now that network cards start coming with UDI drivers
on a diskette as a matter of course. The UDI device driver uses a
standardized, well-defined interface --- the UDI interface. It really
isn't all that different from the Linux kernel calling system BIOS
routines, or the APM routines.

So fundamentally, I don't have a problem with the UDI concept --- just
as I don't have a problem with purchasing commercial software to run on
my Linux box. I am not an Open Source fanatic. All other things being
equal, I prefer Open Source, of course, but if a Open Source product
doesn't exist, and there is a good propietary solution available, I will
use it.

The big question, though is the quality of the UDI reference
implementation which SCO is planning on writing. WIll it be clean
enough so that Linus is willing to include it in the mainline kernel?
That's the $64,000 question. If it's big, ugly, etc., then the answer
will be no. And of course, the UDI reference implementation which will
actually *allow* the Linux kernel to take advantage of UDI drivers will
have to be GPL'ed, since that *will* be linked with the kernel in a very
fundamental way. But as far as I can tell, SCO understands that.

- Ted

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