Preparing final bootloader swap: symlinkat: Operation not permitted

[goldyfruit]

Hi,

I'm trying to build a custom rootfs for my Raspberry Pi 4B 64-bit using multistrap and deploy it via ostree admin deploy via a HTTP OSTree repository.

The build works fine (even If I think I missed few things) but when I try to deploy the tree on my RPi I got this error:

sudo ostree admin deploy --os=debian rpi/debian/stable/arm64 -vvv
OT: Preparing transaction in repository 0x5597508000
OT: Pushing lock non-blocking with timeout 30
OT: Creating repo lock table
OT: Opening repo lock file
OT: Push lock: state=unlocked, depth=0
OT: Locking repo shared
OT: Using new tmpdir staging-ae7ca82b-90f5-4160-8194-987727f46a5a-xyZ6ls
OT: Committing transaction in repository 0x5597508000
OT: txn commit staging-ae7ca82b-90f5-4160-8194-987727f46a5a-xyZ6ls
OT: Popping lock non-blocking with timeout 30
OT: Pop lock: state=shared, depth=1
OT: Unlocking repo
OT: boot is ro: no
OT: Using bootloader: (none)
OT: Free lock: state=unlocked, depth=0
OT: Closing repo lock file
OT: Free lock table
error: Preparing final bootloader swap: symlinkat: Operation not permitted

The problem is that /boot partition is vfat and symlinks cannot be created on this filesystem and during the ostree admin deploy I think /boot/ostree try to be created.

I tried to follow the information from @starnight provided in this issue #2223 (I opened) but I'm kind of stuck.

Any idea?

[goldyfruit]

The more I search for a solution the more I think it's related to my rootfs.
What will be the "best" tool/solution to build rootfs based on Debian for Raspberry Pi?

[starnight]

The problem is that /boot partition is vfat and symlinks cannot be created on this filesystem and during the ostree admin deploy I think /boot/ostree try to be created.

Yes! "vfat does not support link" is the key point.

Endless OS has two partitions on RPi 4B's SD card.

SD card

• boot partition (FAT)
  • A folder has RPi firmware files, config files and u-boot (u-boot will find the boot.scr in the rootfs system partition's /boot/ by enumerating partitions)
• rootfs system partition (ext4)
  • /boot/ (not the boot partition)
    • boot.scr (u-boot script)
    • ostree/
      • the OSTree layer/snapshot ...
    • uEnv.txt
    • ...
  • /dev/
  • /etc/
  • /lib/
  • /ostree/
  • /sys/
  • /sysroot/
  • /usr/
  • ...

For this case in Endless OS, OSTree only plays things in the rootfs system partition, and does not touch the things in the boot partition.

[goldyfruit]

@starnight Thanks for the information, this is exactly what I'm trying to achieve with all this information in mind.
How can I prevent ostree admin deploy to write in /boot?

Then I think it has something to do with the way I initialize OSTtree on the client.

ostree admin init-fs /

Does it seems correct for you or do I need to replace / by a different directory?

[GrabbenD]

Did you ever find a good solution @goldyfruit?
Looks like there's some work around this here: #1967

[goldyfruit]

Did you ever find a good solution @goldyfruit?
Looks like there's some work around this here: #1967

No I didn't.

[GrabbenD]

Gnome managed to get Raspberry Pi 4 to work with help of U-Boot as demonstrated here:
https://gitlab.gnome.org/rmader/gnome-build-meta/-/blob/gnome-43/elements/boards/raspberrypi-4/image.bst

They're also setting up a QEMU VM which skips bootloader creation altogether and instead they just copy over relevant files to /boot (which seems to be useful for oneshot setup but you'd have to tweak it to get atomic updates to work properly if I've understood it correctly):
https://gitlab.gnome.org/rmader/gnome-build-meta/-/blob/gnome-43/elements/vm/image.bst