[Bug 1765628] Re: Create an image for all raspberry models

[Adam Smith]

Oliver, thanks for the comment.  Interesting that core has started to
implement this.  I don't know much about snaps/gadgets.

The rpi2 u-boot is supposed to work with the pi3 if the pi3-miniuart-bt
overlay is used.  However, the single u-boot file opensuse uses appears
to be doing something clever.  It is either using and acting on the
device tree that is passed to it by the firmware, or it is detecting if
I have a serial cable connected.

The way Ubuntu classic boots the pi could do with an overhaul.  It is
overcomplicated for no benefit that I can see.  I'm willing to put a bit
of work into the classic images if there is a consensus on what should
be done.  It seems pointless blindly coming up with patches at the
moment.

I think flash-kernel should be dropped since it breaks on every board
revision and it can't handle overlays.  It wouldn't be hard to come up
with some simple kernel hooks and put them in linux-firmware-raspi2.
This is what Debian's raspi3-firmware package should of done, but they
went crazy over the top.

u-boot as implemented at the moment brings no benefit over the pi's
built in firmware bootloader.  u-boot should load the latest kernel from
/boot or provide a menu or something useful.  If it does none of these
things then it should be got rid of.

My preferred long term goal would be for Ubuntu to adopt grub2 on arm.
This is what opensuse uses (via u-boot acting as uefi).  As far as I can
tell grub 2 cannot handle overlays at the moment.  U-boot can load
overlays, but Fedora, opensuse and Ubuntu all use the pi's firmware to
apply overlays.  This could continue, with linux-firmware-raspi2
updating the dtbs/overlays files on /boot/efi or /boot/firmware when
appropriate (e.g. an update from 18.10 to 19.04).

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https://bugs.launchpad.net/bugs/1765628

Title:
  Create an image for all raspberry models

Status in livecd-rootfs package in Ubuntu:
  New

Bug description:
  Currently (Xenial to Bionic) server images only run on the raspberry
  pi 2.  This is due to the u-boot bootloader.

  However it is possible to produce one image that runs on a pi 2 and 3.
  Fedora arm 32 bit produce such an image.  They make use of conditional
  filters in the config.txt
  (https://www.raspberrypi.org/documentation/configuration/config-
  txt/conditional.md ) and put two versions of u-boot on the image.

  They other way to do it is to remove u-boot entirely and just rely on
  the internal pi bootloader to sort it out.  This could be permanent,
  or just for first boot where upon flash-installer is called to install
  the correct u-boot file.

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