Subject: Re: How to ship binary proprietary modules?
From: Arjan van de Ven <arjan@infradead.org>
To: Arne Henrichsen <ahenric@gmail.com>
Cc: linux-kernel@vger.kernel.org
In-Reply-To: <605a56ed041103045027f52b73@mail.gmail.com>
References: <605a56ed041103045027f52b73@mail.gmail.com>
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Date: Wed, 03 Nov 2004 14:03:21 +0100
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On Wed, 2004-11-03 at 14:50 +0200, Arne Henrichsen wrote:
> Hi,
> 
> I would like to get some clarification on how to ship binary
> proprietary modules.
> 

First of all you should really talk to your lawyer about if and how you
can do this legally.

> I did compile my module under linux 2.6.8.1. and loaded it under
> 2.6.9. From what I understand of versioning it should check if the
> software interface is valid still and then allow the module to be
> loaded. Surely between version 2.6.8.1 and 2.6.9 nothing that drastic
> changed?

A *lot* of things changed.


> Or do I totally misunderstood versioning? 

Yes; basically versioning checks are a very rough approximation of a
check on ABI. Linux does not keep abi for modules at all, every single
release and a whopping lot of config options each result in an entirely
different ABI. Heck even most bugfixes will change the abi.


> Must a customer for instance
> request the module compiled for a specific kernel?

yes; however you're much better off shipping the sourcecode of your
module, or if your lawyer allows that (there may be some patent issues
involved), you can choose to ship a .o file and a glue layer, where the
glue layer abstracts the kernel ABI/API away entirely.


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