[yocto] Minimalist Initrd

[Jeremy Moles]

Hey guys! I've been using Yocto for a while now and it's quite 
phenomenal; I really appreciate the hard work and effort the community 
puts into this project, and I hope I can (with the approcal of my 
clients) return some of my own Yocto/OE (and specifically, Angstrom) 
work back for everyone to use!

I've encountered a scenario wherein I have only (and this constraint 
can't be worked around) 13MB of space into which I can place a JFFS2 
image which can be used to continue the system startup (which is 
initially started by an older version of uboot).

I'm having trouble finding a clean solution within the Yocto/OE world 
for this issue. Thus far, I've been using an old, generic, super-tiny 
ARM-based initrd I made years ago which just does a few (proprietary) 
things in the linux and then fires off /sbin/init in the "real" filesystem.

What I need now, however, is a recipe (or perhaps hints on where to 
start when rolling my own recipe) for generating little more than an 
image (JFFS2 or cpio.gz) with busybox in it. I can handle the rest view 
function overrides, I just need the base startup.

Can anyone give me any hints on this? I'm using Poky mostly, which some 
forrays into Angstrom 2016. Any hints on existing bitbake recipes I can 
inherit/adapt would be amazingly useful. Thanks!