[maemo-developers] N900 kernel module recompile

[From: Nils Faerber]

Hi all!
After all that RPM vs DEB debate I thought I could bring up something
more productive ;)

I would like to hack on some drivers on the N900, so I need to be able
to recompile kernel modules. Ideally I would like only to replace
modules, not the whole kernel+modules package.

So what I did was I installed the Maemo5 SDK first in order to get the
proper toolchain.
Then I took a vanilla 2.6.28 Linux kernel archive and applied the kernel
patch from
	http://repository.maemo.org/pool/fremantle/free/k/kernel/
	kernel_2.6.28-20094803.3+0m5.diff.gz

Then I setup my comile environment:

export PATH=/scratchbox/compilers/cs2007q3-glibc2.5-arm7/bin/:$PATH
export CROSS_COMPILE=arm-none-linux-gnueabi-
export ARCH=arm

Then kernel config:
cp arch/arm/configs/rx51_defconfig ./.config
make oldconfig

A "make modules" does cleanly compile the modules. Fine so far (except
for that te modules are *huge* and a "arm-none-linux-gnueabi-strip -R
.not -R .comment --strip-unneeded" seems reasonable).

But when I try to load one of the new modules I get:
	-1 Invalid module format
And dmesg shows:
	"no symbol version for struct_module"

This usually means that CONFIG_MODVERSIONS is not set but I double
checked that and I do have "CONFIG_MODVERSIONS=y" in ".config".

I also changed the extra version name in the kernel toplevel Makefile,
which should be correct (to my knowledge):

#NAME = Erotic Pickled Herring
NAME = maemo

There is an older page about recompiling kernel for Diablo in the Wiki:
	http://wiki.maemo.org/Compiling_the_kenrel
Would that still apply (of course replacing Diablo with Freemantle and
N810 with N900 or RX51 respectively)?

Again, I just want to hack on one single module. So I would like to
avoid having to flash a completely home-grown kernel+modules set
(frankly that scares me a little ;)


Any hint would be really appreciated ;)
Some N900 kernel hackers around here?

Ideally I would like to make my changes available again so that others
can also play with them by just replacing a single .ko-module...

Cheers
  nils

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