linux-kernel - Re: Inserting code from userspace to kernel space

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Message-ID: <alpine.DEB.1.00.0805242244290.2200@OLPC>
Date:	Sat, 24 May 2008 22:44:37 -0700 (PDT)
From:	Alex Belits <abelits@...bos.illtel.denver.co.us>
To:	Bosko Radivojevic <bosko.radivojevic@...il.com>
cc:	lkml <linux-kernel@...r.kernel.org>
Subject: Re: Inserting code from userspace to kernel space

On Thu, 22 May 2008, Bosko Radivojevic wrote:

> I'm looking for a way to insert code from user space to the kernel
> space, but without using kernel module. Actually, we are working on a
> system that has to allow end user to change part of code (one or two
> functions) that is executed from the kernel space.
>
> For now we have two different kernel modules, one exporting a function
> which another module uses. Process of compiling kernel module is quite
> ineligible for standard end user (along with the requirement to
> support multi platform cross compiling) compared to just cross
> compiling a simple code that doesn't use any libraries than libc.

Why? You don't have to recompile everything, just link a module before 
loaing it -- a part containing the function can be one object file, the 
rest of the module (a wrapper) is compiled once for a particular kernel 
version, and both are linked together, producing a module valid for a 
particular kenel version.

This is how most of proprietary drivers are distributed, and Ubuntu has a 
whole infrastructure around that mechanism that simplifies transition 
between versions.

-- 
Alex
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