Date: Tue, 12 Jun 2007 08:12:35 -0700
From: Randy Dunlap <randy.dunlap@oracle.com>
To: "Federico Paparoni" <federico.paparoni@gmail.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Linux kernel 2.4 programming problem
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On Tue, 12 Jun 2007 15:54:57 +0200 Federico Paparoni wrote:

> Hi all,
> i'm trying to create a simple system call in a kernel 2.4 distribution.
> I read guide/articles like this
> 
> http://irfanhabib.wordpress.com/2006/10/01/adding-a-system-call-linux-24x/
> 
> All the articles say the same things, but the implementation of my new
> system call doesn't work.
> I create a new entry in arch/i386/kernel/entry.S
> I create a new entry in include/asm/unistd.h
> I create a new function with the asmlinkage prefix in a source file
> already defined (in ipc/sem.c for example)
> 
> When i create my user program, it doesn't work. Firstly when i try to
> compile i receive a problem like this
> 
> : undefined reference to 'errno'
> 
> Then I include errno.h (also if i don't understand this step) and the
> compilation works, but the syscall neverworks, because the call always
> return -1.
> 
> Any help?
> Any tutorial FOR DUMMY MAN that someone already used?

You can try this one.  It used to work, but I haven't updated or
tested it lately.

http://www.xenotime.net/linux/syscall_ex/

---
~Randy
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