The asymmetric slots scenario support for raspberry pi 4

[SocialLoginDev]

I try using the asymmetric slots scenario.
My system.conf:

[system]
compatible=RaspberryPi4
bootloader=uboot
data-directory=/data/

[keyring]
path=/etc/rauc/ca.cert.pem
 
[slot.update.0]
device=/dev/mmcblk0p2
type=raw
bootname=update

[slot.main.1]
device=/dev/mmcblk0p3
type=ext4
bootname=main

and wks.in:

part /boot --source bootimg-partition --ondisk mmcblk0 --fstype=vfat --label boot --active --align 4096 --size 100
part /update --size 100 --ondisk mmcblk0 --fstype=ext4 --label update --align 4096
part / --source rootfs --ondisk mmcblk0 --fstype=ext4 --label main --align 4096
part /data --size 100 --ondisk mmcblk0 --fstype=ext4 --label data --align 4096

What else needs to be fixed and what additional files need to be changed for everything to work properly?

[ejoerns]

@SocialLoginDev It might require less adaptions if you name your main.1 slot rootfs.0 instead.
Otherwise, you would also need to update the update-bundle.bb recipe to emit a slot of name main (instead of rootfs).

You may also want to update the bootloader script (recipes-bsp/rpi-u-boot-scr/files/boot.cmd.in:). It currently has a logic for symmetric updates and uses A and B as boot names (instead of update and main). For the recovery case, one might be able to simplify the boot logic to "boot A (or main) N times, otherwise boot fallback/update".

[SocialLoginDev]

I have updated the update-bundle.bb recipe:

DESCRIPTION = "RAUC bundle generator"

inherit bundle

RAUC_BUNDLE_COMPATIBLE = "RaspberryPi4"
RAUC_BUNDLE_VERSION = "v20240001"
RAUC_BUNDLE_DESCRIPTION = "RAUC datafox bundle"

RAUC_BUNDLE_FORMAT = "verity"

RAUC_BUNDLE_SLOTS = "main" 
RAUC_SLOT_main = "core-image-base"
RAUC_SLOT_main[fstype] = "ext4"

RAUC_KEY_FILE = "${THISDIR}/files/development-1.key.pem"
RAUC_CERT_FILE = "${THISDIR}/files/development-1.cert.pem"

and recipes-bsp/rpi-u-boot-scr/files/boot.cmd.in:

fdt addr ${fdt_addr} && fdt get value bootargs /chosen bootargs

test -n "${BOOT_ORDER}" || setenv BOOT_ORDER "main update"
test -n "${BOOT_MAIN_LEFT}" || setenv BOOT_MAIN_LEFT 3
test -n "${BOOT_UPDATE_LEFT}" || setenv BOOT_UPDATE_LEFT 3
test -n "${BOOT_DEV}" || setenv BOOT_DEV "mmc 0:1"

setenv bootpart
setenv raucslot

for BOOT_SLOT in "${BOOT_ORDER}"; do
  if test "x${bootpart}" != "x"; then
    # skip remaining slots
  elif test "x${BOOT_SLOT}" = "xmain"; then
    if test ${BOOT_MAIN_LEFT} -gt 0; then
      setexpr BOOT_MAIN_LEFT ${BOOT_MAIN_LEFT} - 1
      echo "Found valid RAUC main slot"
      setenv bootpart "/dev/mmcblk0p3"
      setenv raucslot "main"
      setenv BOOT_DEV "mmc 0:3"
    fi
  elif test "x${BOOT_SLOT}" = "xupdate"; then
    if test ${BOOT_UPDATE_LEFT} -gt 0; then
      setexpr BOOT_UPDATE_LEFT ${BOOT_UPDATE_LEFT} - 1
      echo "Found valid RAUC update slot"
      setenv bootpart "/dev/mmcblk0p2"
      setenv raucslot "update"
      setenv BOOT_DEV "mmc 0:2"
    fi
  fi
done

if test -n "${bootpart}"; then
  setenv bootargs "${bootargs} root=${bootpart} rauc.slot=${raucslot}"
  saveenv
else
  echo "No valid RAUC slot found. Resetting tries to 3"
  setenv BOOT_MAIN_LEFT 3
  setenv BOOT_UPDATE_LEFT 3
  saveenv
  reset
fi

fatload mmc 0:1 ${kernel_addr_r} @@KERNEL_IMAGETYPE@@
if test ! -e mmc 0:1 uboot.env; then saveenv; fi;
@@KERNEL_BOOTCMD@@ ${kernel_addr_r} - ${fdt_addr}

RAUC only works from the update partition; when I try to update from the main partition, it displays the following message:
LastError: Installation error: No target slot for class main of image core-image-base-raspberrypi4-64.ext4 found
Is this normal behavior?

[SocialLoginDev]

Another question: How to change the update partition to initramfs? In my case, I already have initramfs, it is used to overlayroot the main system using the initramfs-module-overlayroot script. What should be done in this case?