Re: Tainted Modules Help Notices

From: Morgan Collins [Ax0n] (
Date: Wed Oct 10 2001 - 15:28:21 EST

> I was under the same impression about the module licensing tagging. I
> had read that it was suppose to be for maintainability (.i.e. source available so
> kernel gods can debug) and not to enforce ideological conformity. Now I read that
> anything not licensed under the GPL, including BSD or simply public domain source
> code, will taint my kernel and modprobe complains about non-GPL stuff including
> parport_pc which apparently did not have a license. Should I expect a Linux kernel
> KGB to show up next?
I think what has happened here is a little bit of a misunderstanding.

I think that the modprobe source and the kernel source just aren't in sync with the
development of the new (re DEVELOPMENTAL) MOD_LICENSE() implementation.

Weither or not the BSD-NAC is GPL compatible has already been determined, as it's in the
kernel and the lead developers have said so. I trust them, they'll get sued if they don't
look at things like that. Modprobe told me a BSD module was tainted, I assumed that ment
it was incompatible with the kernel which is GPLed. I shouldn't trust everything I read :>

The problem lies in modprobe not having it in it's list of licenses to not mark as tainted.

When I modprobe ppp_deflate, it does not fail to load, it simply warned me that my kernel
would be tainted. What does having a tainted kernel mean? It is to tell kernel
debuggers if this is a clean kernel or if anything unusual has occurred.

> Furthermore I have to agree with the previous poster. Any module could
> easily lie to MODULE_LICENSE about its licensing terms and that would not make it's
> source automatically "free" and GPLable so I am now wondering if this tainting
> mechanism is of any use at all.
If the purpose was to discriminate against licensing, I would agree. But since
non-compatible source is not distributed with the kernel, and the mechanism is for
debugging, what is the purpose of lying to the kernel? To confuse debuggers? No point in that.

> Just out of curiosity do all of these license tags in the modules take
> up any permanent kernel memory, especially in a heavily modularize system?
A grep of /proc/kcore only showed the MODULE_LICESE in this email, and the scrollback
buffer in my xterm, so I don't think so.

Morgan Collins [Ax0n]
Software is something like a machine, and something like mathematics, and something like
language, and something like thought, and art, and information.... but software is not in
fact any of those other things.

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