[Merge] ~vorlon/livecd-rootfs:subarch-manifest into livecd-rootfs:ubuntu/master

[Loïc Minier]

("generic": thanks! makes sense)

> So to confirm: from your side, you don't see any problems with a hard-coded
> list that would need to be extended in livecd-rootfs every time Partner
> Engineering needs to stand up a new image? Is this because you expect to
> already have to touch the livecd-rootfs code?

It's hard to tell how much of a problem it would be at scale, but it seems a relatively minor annoyance to have to list one new subarch every time we have a new image right now. At least for our current partneships, the number of target images has been relatively small, albeit it's possible this changes in the future with new partnerships. The riscv images are growing much faster for one! :-)

In general, there's also pressure to keep images generic for the purpose of ODMs and certification programs downstream of these images.

So perhaps a good long term motivation that would support both trends is to leverage subarch and separate images for some non-trivial platform enablement that need different kernels, or selection of userspace packages – and perhaps in the future also for different sub-ISAs if we go there. And then perhaps we can avoid multiplying images and subarches for every new board with a slightly modified u-boot / device tree and we somehow combine firmwares with OS images, after validating each separately a bit more. This opens lots of questions of course around tooling and lifecycle of firmware vs images, perhaps a good spec or meeting topic for us all! Heinrich and Łukasz would certainly be interested amongst a few others  :-)
-- 
https://code.launchpad.net/~vorlon/livecd-rootfs/+git/livecd-rootfs/+merge/451944
Your team Ubuntu Core Development Team is subscribed to branch livecd-rootfs:ubuntu/master.