[yocto] Custom recipe kernel 2.6.32 and depmodwrapper

[Javi Roman]

Hi!

I've found a possible issue with the depmodwrapper (in image.bbclass
-> do_rootfs) and the old kernel tree 2.6.32.

The final rootfs image is not properly populated with the necessary
kernel module files for the module-init-tools utility:

/lib/modules/<kernel-version/
modules.alias
modules.alias.bin
modules.builtin
modules.builtin.bin
modules.dep
modules.dep.bin
modules.devname
modules.order
modules.softdep
modules.symbols
modules.symbols.bin

This tool depmodwrapper is using the kernel Makefile generated file
"modules.builtin", this file is not generated by the kbuild kernel
system in the 2.6.32 kernel. This feature was included in the 2.6.33
branch [1].

So the image.bbclass is broken for kernel trees below 2.6.33 version.
However the bitbake.conf shows the variable OLDEST_KERNEL = "2.6.16".

Many thanks!

[1] https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=bc081dd6e9f622c73334dc465359168543ccaabf

Javi Roman