[clug] The GPL and kernel modules

Peter Barker pbarker at barker.dropbear.id.au
Wed Jun 21 01:17:33 GMT 2006

On Wed, 21 Jun 2006, Robert Edwards wrote:

> I'm wondering if it might not be technically feasible to move
> some of these binary-only kernel modules into user-space and
> provide necessary hooks across some virtualisation scheme into

You might like to read up on this OpenBSD wireless driver:

Quick summary is that passing stuff off to a userland app caused massive 
bloatage (well... perhaps "contributed to" would be closer?).

> kernel space to actually talk to the hardware? I know that so-
> called micro-kernels take this approach. If someone where to
> provide the necessary API, would it then violate the GPL to
> have binary-only code working with that API across into the
> kernel?

I believe this has been hashed out a bit elsewhere (LKML?), but you could 
start with a base case of someone writing a "pass through" kernel module 
which just happens to export all the symbols to userland that you need to 
write your restricted binary - but all the symbols do is wrap kernel 
calls. How much do you need to change that module before you wouldn't call 
it a "derivative work"?

Additionally - there are already ways to define licenced "interfaces" 
in the kernel - "EXPORT_SYMBOL" and "EXPORT_SYMBOL_GPL".... I'm not sure 
what the policy on using one or the other is.

Lastly.... the /kernel/ is supposed to be the layer between the hardware 
and userland. Passing stuff verbatim between the hardware and userland is 
stuff we're supposed to be moving /away/ from :) People are still hoping 
that Xorg will do that shortly!

> Bob Edwards.

Peter Barker                          |   N    _--_|\ /---- Barham, Vic
Programmer,Sysadmin,Geek              | W + E /     /\
pbarker at barker.dropbear.id.au         |   S   \_,--?_*<-- Canberra
You need a bigger hammer.             |             v    [35S, 149E]
"Peter is apathetic, and I'm vaguely apathetic" -- Rachel, thinking of organising a movie trip

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