[Pkg-raspi-maintainers] Raspberry Pi 3 running armhf!

[Tianon Gravi]

Howdy fellow Debian Pi-ers!

This coming week at work I'm likely going to be trying to get a stack
of Raspberry Pi 3s to run the "armhf" port of Debian (rather than
arm64, as has been done in most of the previous work).

I've identified a couple places I'm going to need to make
modifications so far, but was curious whether there were maybe more
things I'm missing. :)

The two main places I've identified changes needing to be made are in
"flash-kernel" and "raspi3-firmware" (which I'll need from sid to even
get armhf; maybe worth considering a stretch-backport at some point?
O:>).

In "flash-kernel", I'm anticipating needing to add something like the
following to "/etc/flash-kernel/db": (adapted from [1], just adding
"armmp-lpae" to the flavors)

    Machine: Raspberry Pi 3 Model B
    Kernel-Flavors: arm64 armmp-lpae
    DTB-Id: bcm2837-rpi-3-b.dtb
    U-Boot-Script-Name: bootscr.uboot-generic
    Required-Packages: u-boot-tools
    Boot-Script-Path: /boot/boot.scr

[1]: https://bugs.debian.org/cgi-bin/bugreport.cgi?att=1;bug=869488;filename=0001-Add-a-machine-db-entry-for-the-Raspberry-Pi-3-Model-.patch;msg=15

And in "raspi3-firmware", adjusting
"/etc/kernel/postinst.d/raspi3-firmware" to use "bcm2837-rpi-3-b.dtb"
even though I'm on "armhf" (as hinted by vagrant in [2]).  I'm sort of
wondering whether we could convince flash-kernel to tell us which DTB
we should be using, since it should know, but I'm going to be more
concerned with making it actually work initially. :)

[2]: https://bugs.debian.org/858428#58

Hopefully I'm not missing anything major and will have some kind of
successful result out of this!

If I manage to get something that actually works, do you think this
sort of configuration is something worth supporting officially?  I'd
be happy to file bugs with patches if I do manage to get it actually
running properly!

As a final note, thanks for all the work making Debian support the
Raspberry Pi family directly without Raspbian (the Raspberry Pi 3 I
have here at home is happily running arm64 Debian). :)

(I've also now subscribed to this list, but being explicitly CC'd for
any replies also doesn't bother me.)

♥,
- Tianon
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