[Pkg-raspi-maintainers] Bug#989838: needs adaptation to EFI-booted Debian on Raspberry Pi 4

[Marc Haber]

Package: raspi-firmware
Version: 1.20210303+ds-1
Severity: wishlist

Hi,

I am currently trying to get the Raspberry Pi 4 running with Debian
bullseye booted via EFI. The instructions to do so are on
https://www.raspberrypi.org/forums/viewtopic.php?t=282839

I find this especially joyful because it allows to use a plain,
unchanged Debian installer using the "normaL" bullseye
netinst_arm64.iso, and one ends up with a Raspberry Pi booting via a
stock grub-efi-arm64 boot manager, including all Debian magic.

It looks like /etc/kernel/postinst.d/z50-raspi-firmware needs some
adaption to be able to support the installed system. For example, on the
EFI Debian, what is in /boot/firmware on a "normal" Raspi Debian is in
/boot/efi/firmware, and z50-raspi-firmware expects /boot/firmware to be
a mounted vfat filesystem (cf #948712). I have solved this by
bind-mounting /boot/efi/firmware to /boot/firmware, and installation of
a new kernel finishes alright now. Probably a lot of the code in
z50-raspi-firmware is not needed on a system booting via EFI and grub.

I guess that there are other assumptions that are different on an
EFI-based Raspbery Pi installation. Would you be interested in me
helping with these issues or do you consider EFI booting out of scope of
the raspi-firmware package?

This being said, my EFI-booted Raspberry Pi doesn't start into X11.  I
don't see any log entries regarding the vc4 module despite it being
loaded, and I suspect that this is some issue with the firmware not
getting properly loaded. My system is also missing the
"raspberrypi-firmware soc:firmware: Attached to firmware from
2021-02-25T12:10:40" dmesg entry that a working Raspberry Pi using
Gunnar's tested image from 2021-04-13 has. I cannot find the string
"Attached to" in any file in the raspi-firmware package.

Can you enlighten me which step of the system boot emits this message?
It usually comes around the 4 second mark, so it is pretty early in
bootup, deeply inside the initramfs. Since the initramfs on Gunnar's
image doesn seem to contain any firmware, I guess the firmware is
actually loaded from the /firmware directory BEFORE Linux is even
started, right?

Or is this probably related to the EFI system using ACPI instead of
device trees? The "installing Debian EFI on Raspberry" mentions some
drivers not being able to detect their hardware because they just work
with device trees instead of ACPI. Could this be the case for the vc4
driver as well?

Would a Raspberry Pi 4 boot up at all with firmware being in the wrong
place?

Greetings
Marc

P.S.: Is there a mailing list and/or an IRC channel regarding Debian on
Raspberry Pi?