Kernel flavors specified that aren't in Ubuntu

[Will Ross]

Each entry in the flash-kernel database specifies which kernel flavors are applicable for each machine type. Upstream (Debian) has separate flavors for it's 32-bit ('armmp' and 'armmp-lpae') and 64-bit ('arm64') ARM kernels, while Ubuntu uses the 'generic' (and 'generic-lpae') kernel flavors. This causes a failure during dpkg install, as flash-kernel is unable to find the correct kernel and errors out. There's also kernel flavors mentioned in the flash-kernel database that don't have an equivalent in Ubuntu (ex: mx5, exynos5, keystone).

As far as a concrete bug:
flash-kernel on Ubuntu fails to install cleanly on BeagleBone Black with the 'generic' kernel flavor installed. A workaround is to add an override in /etc/flash-kernel/db that specifies the 'generic' kernel flavor as allowed:

Machine: TI AM335x BeagleBone
Machine: TI AM335x BeagleBone Black
Kernel-Flavors: generic
DTB-Id: am335x-boneblack.dtb
Boot-Script-Path: /boot/boot.scr
U-Boot-Script-Name: bootscr.beaglebone
Required-Packages: u-boot-tools

[Dave Jones (waveform)]

Can I ask which Ubuntu image you're using with the BBB?

Generally speaking, we only change those entries in all.db for boards which Ubuntu explicitly supports, but perhaps we should be doing this for more boards if (otherwise) things "just work".

[Will Ross (paxswill)]

I'm not currently using that board, but I can bring it back up if needed for testing/reproduction.

I wasn't using a prebuilt image, I was installing Ubuntu using debootstrap (IIRC, booted originally with the 18.04 based image provided [0], or "cross" installed originally from a Debian image).

So totally unsupported, and for the specific case of the BeagleBone Black there were some issues with Ubuntu's u-boot (something about old configuration flags for the SPL?), but I do think making the change would be helpful as for other boards it does "just work".

0: https://elinux.org/BeagleBoardUbuntu#All_BeagleBone_Variants_and_PocketBeagle

[Dave Jones (waveform)]

Fair enough; we do need to tidy up all the kernel flavours that *aren't* supported in Ubuntu anyway (I think the keystone one got removed fairly recently, but the rest should be too). And it'd be nice to make things a bit easier for those wishing to experiment with Ubuntu even on unsupported platforms. I'll take a look when the archive opens for K-animal

[Dave Jones (waveform)]

This was fixed by @vorlon in 3.106ubuntu4 which unconditionally remaps the "armmp" flavor in all.db to "generic":

https://launchpad.net/ubuntu/+source/flash-kernel/3.106ubuntu4