**Confirmed successful A/B kernel upgrade on Raspberry Pi 3B+ with a manual systemd 259 workaround**
I can confirm a successful A/B kernel upgrade on a Raspberry Pi 3 Model B Plus running Ubuntu 26.04.1 LTS (arm64), using a manual workaround for the reboot argument incompatibility described in this bug report. ### Test environment - Hardware: Raspberry Pi 3 Model B Plus Rev 1.3 - OS: Ubuntu 26.04.1 LTS (resolute), arm64 - `piboot-try`: `1.1ubuntu0.1` - `systemd`: `259.9-0ubuntu0.1` - Previous kernel: `7.0.0-1017-raspi` - New kernel: `7.0.0-1020-raspi` (`linux-image-raspi 7.0.0-1020.20`) - Boot medium: SD card, 505 MB FAT boot partition The installed `/usr/share/flash-kernel/functions-piboot` still contains the problematic invocation at line 411: ```sh reboot "$boot_partition tryboot" ``` ### Initial state Following the kernel upgrade: ```text Running kernel: 7.0.0-1017-raspi current/state: good new/state: unknown old/: absent piboot-try-reboot.service: masked piboot-try-validate.service: enabled ``` The boot configuration contained: ```ini # autoboot.txt [all] tryboot_a_b=1 ``` ```ini # config.txt [all] os_prefix=current/ [tryboot] os_prefix=new/ ``` The bootloader reported: ```text tryboot: 0 partition: 0 ``` `piboot-try --test` returned exit status 0, confirming that untested boot assets were available. ### Workaround performed The automatic `piboot-try-reboot.service` was masked to avoid the incompatible reboot invocation. After backing up the boot files, the following operation was performed: ```sh sudo sh -c ' set -e test "$(cat /boot/firmware/current/state)" = good test "$(cat /boot/firmware/new/state)" = unknown test "$(systemctl is-enabled piboot-try-reboot.service)" = masked printf "trying\n" > /boot/firmware/new/state sync systemctl reboot --reboot-argument="0 tryboot" ' ``` The Raspberry Pi successfully booted the new kernel, and the standard Ubuntu `piboot-try-validate.service` completed the promotion of the new boot assets. ### Observed result After reconnecting via SSH: ```text $ uname -r 7.0.0-1020-raspi ``` The journal contained: ```text Nov 01 11:47:09 ipfs3 systemd[1]: Starting piboot-try-validate.service ... Nov 01 11:47:11 ipfs3 piboot-try[910]: Switched new boot assets to current successfully Nov 01 11:47:11 ipfs3 systemd[1]: Finished piboot-try-validate.service ... ``` Final verification: ```text Running kernel: 7.0.0-1020-raspi piboot-try-reboot.service: masked piboot-try-validate.service: enabled current/state: good new/: absent old/state: good systemctl --failed: 0 failed units ``` ### Conclusion This test confirms that a complete A/B kernel upgrade, including successful validation and promotion of boot assets, is possible on a Raspberry Pi 3B+ under systemd 259.9 when the incompatible reboot invocation is bypassed. The second issue described in this report, involving failure to boot from the `new/` slot even with an explicit tryboot request, **was not reproduced on this Pi 3B+**. This does not rule out that issue on the originally reported Compute Module 4 hardware. The test does not constitute a fix for the packaged `piboot-try` implementation. Version `1.1ubuntu0.1` still contains the incompatible invocation, and the automatic reboot service remains masked on this system. I hope these results help distinguish the systemd reboot-argument incompatibility from potentially hardware- or firmware-specific problems with the A/B boot mechanism. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2167775 Title: Ubuntu 26.04 on Raspberry Pi CM4: A/B kernel updates never apply To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/piboot-try/+bug/2167775/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
