[oe] OE builds LKMs not matching kernel version (MACHINE="dm6446-evm")

[Bjørn Forsman]

Hi all,

I'm using MACHINE="dm6446-evm" and DISTRO="angstrom-2008.1" and OE
builds different/incompatible versions of the kernel modules (LKM) and
the kernel. How do I go about debugging this?

The built images seem correct on the host (same version number):

uImage-2.6.31+2.6.32-rc2-r28+gitr7b2683fd0168df1576fcea947ef9f63e905de807-r28-dm6446-evm.bin
modules-2.6.31+2.6.32-rc2-r28+gitr7b2683fd0168df1576fcea947ef9f63e905de807-r28-dm6446-evm.tgz

But when booting the target, the kernel complains because the LKMs
doesn't match the kernel version:
----
WARNING: Couldn't open directory
/lib/modules/2.6.32-rc2-09211-g17d857b: No such file or directory
FATAL: Could not open
/lib/modules/2.6.32-rc2-09211-g17d857b/modules.dep.temp for writing:
No such file or directory
WARNING: Couldn't open directory
/lib/modules/2.6.32-rc2-09211-g17d857b: No such file or directory
FATAL: Could not open
/lib/modules/2.6.32-rc2-09211-g17d857b/modules.dep.temp for writing:
No such file or directory
...snip...
# ls -l /lib/modules
drwxr-xr-x    3 root     root         4096 Dec  9 00:10 2.6.32-rc2-davinci1
# insmod /lib/modules/2.6.32-rc2-davinci1/kernel/fs/smbfs/smbfs.ko
[  264.580000] smbfs: disagrees about version of symbol module_layout
insmod: cannot insert
'/lib/modules/2.6.32-rc2-davinci1/kernel/fs/smbfs/smbfs.ko': invalid
module format
# uname -r
2.6.32-rc2-09211-g17d857b
----

I really wish I knew OE well enough to debug this myself, but I don't
(yet). What is the bitbake target for kernel modules? Where is is the
decision on what kernel version to build the LKMs against? How is it
possible for LKMs to end up being built for wrong kernels?

(I have tried to generate a dependency graph with 'bitbake -g
base-image', hoping that it would give me some clues. But my machine
just hangs for a long time and then segfaults when trying to view
depends.dot.)

Best regards,
Bjørn Forsman