[OE-core] Issue with RDEPENDS in module.bbclass for initramfs

[Anders Darander]

We have recently started investigating to make an even smaller build of
our local distro & machine. This smaller build should be run exclusively
from an initramfs, thus we have a need to reduće the size of the rootfs
as much as possible. (Especially as we'd still like some "bigger"
tools/pieces in the initramfs).

However, our first attempt to create a small image turned our to be
larger than expected. After a first investigation, it turns out that our
external kernel modules have an RDEPENDS on kernel-image (this is from
module.bbclass). As we're creating an initramfs-based rootfs, this is
obviously not desired... Locally removeing that RDEPENDS reduces the
image as expected...

I understand that in the general distro case, there is a need to be able
to express a dependency on a certain kernel version. However, I really
don't think that bringing in the kernel-image is a good idea, not an
general embedded platforms at least. (On the x86 this is usually not a
problem, as you almost always have the kernel as a part of the rootfs
anyway).

Could we come up with another way of expressing this dependency? That
would definitely be valuable for the small-ish embedded systems.

Cheers,
Anders

-- 
Anders Darander
ChargeStorm AB / eStorm AB