Re: Over-riding symbols in the Kernel causes Kernel Panic

[Grant Coady <grant_lkml@dodo.com.au>]

On Wed, 23 Nov 2005 19:04:41 +0100, Jesper Juhl <jesper.juhl@gmail.com> wrote:

>On 11/23/05, Bill Davidsen <davidsen@tmr.com> wrote:
>> Ashutosh Naik wrote:
>> > Hi,
>> >
>> > I made e1000 ( or for that matter anything) a part of the 2.6.15-rc1
>> > kernel and booted the kernel. Next I compiled e1000 as a module (
>> > e1000.ko ), and tried to insmod it into the kernel( which already had
>> > e1000 a compiled as a part of the kernel). I observed that
>> > /proc/kallsyms contained two copies of all the symbols exported by
>> > e1000, and I also got a Kernel Panic on the way.
>> >
>> > Is this behaviour natural and desirable ?
>>
>> No, trying to insert a module into a kernel built with the functionality
>> compiled in is a vile perverted act, and probably illegal in Republican
>> states! ;-)
>>
>> The other day I mentioned that reiser4 will find bugs because people
>> will do bizarre things with it when it is more widely used. I think you
>> have hit a "no one would ever do that" bug in the module loader, and
>> demonstrated my point in the process.
>>
>> The panic isn't desirable, but I'm not sure what "correct behaviour"
>> would be, I can't imagine that this is intended to work. The issues of
>> removing such a module gracefully are significant.
>
>Wouldn't the desired behaviour be that when the kernel attempts to
>load a module it checks if it is already present build-in and if so
>simply refuse to load it at all?

But that sounds just too easy to implement, what's the catch?  :o)
-- 
Grant.
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