linux-kernel - Re: Null pointer exception for local variables in stack with C++ kernel modules

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Message-ID: <4D239AE1.10003@bwalle.de>
Date:	Tue, 04 Jan 2011 23:10:41 +0100
From:	Bernhard Walle <bernhard@...lle.de>
To:	Leo Prasath <leo.prasath@...il.com>
CC:	linux-kernel@...r.kernel.org
Subject: Re: Null pointer exception for local variables in stack with C++
 kernel modules

Hello Leo,

Am 04.01.11 20:46, schrieb Leo Prasath:
> 
> I have integrated a C++ codebase which uses minimalistic features of c
> and followed the guidelines in
> http://pograph.wordpress.com/2009/04/05/porting-cpp-code-to-linux-kernel/
> to integrate with an existing C linux kernel module.
> It all works fine except for occassional very very weird NULL pointer
> exceptions.

Wild guess: Stack overflow. In the kernel the stack is very limited
(depends on the configuration and IIRC on the archtecture, but 4K is the
minimum IIRC) and in C++ it's possible and common to put larger objects
on the stack.

However, C++ isn't supported by the kernel developers and you're on your
own. Rewrite the code to use plain C.


Regards,
Bernhard
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