[Gllug] How to check if module is in kernel ?

[Alain Williams]

On Sun, Nov 14, 2010 at 11:40:57PM +0000, Steve Parker wrote:
> On 14/11/10 23:34, salsaman at xs4all.nl wrote:
> > OK, I found the ubuntu equivalent in /boot/config-`uname -r`.
> >
> >    
> http://www.faqs.org/docs/Linux-HOWTO/Kernel-HOWTO.html says "Everytime 
> you compile and install the kernel image in /boot, you should also copy 
> the corresponding config file to /boot area, for documentation and 
> future reference. Do NOT touch or edit these files!!" which suggests 
> that there is no proper storage of that information (I wouldn't have 
> thought that it would cost too much to store a 100Kb .config file in a 
> 2.3Mb kernel (sizes taken from current Debian testing; YMMV)

The file is ascii, on my system it weighs in at some 65KB, gzipping down to 17KB.
I suppose that it could be put into a kernel section that is freed up - like
the initialisation/startup code.

However, think about how the kernel loads - the file is brought into RAM and ungzipped,
run and then the initrd read, unzipped & mounted as a RAM file system.
The extra 17KB might not seem like a lot, but Linux does run on some severly memory
limited machines (think a cheap broadband router) and the use of this memory
could make things awkward - so simpler to not have the problem at all.

I also note that each kernel has another 3 files:
* the symvers file - CRC for all exported symbols
* System.map - kernel symbol table, ie addresses of symbols in the kernel
* initrd -- small initial RFS used to load the modules needed to access the real Root File System (drivers, etc)

So adding a 4th (config) was the obvious thing to do.

-- 
Alain Williams
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