Latest master branch poky-altcfg distro builds for genericarm64 machine and image core-image-base fail to start agetty on AMD KV260 /dev/ttyPS1.

Until recent refactory to systemd's agetty handling, the default config of poky-altcfg was to try starting agetty on all serial consoles set in SERIAL_CONSOLES build time variable but also start systemd agetty generator to spawn agetty on all detected serial consoles.

The result was that poky-altcfg genericarm64 images like core-image-minimal on AMD KV260 booted into serial console login on /dev/ttyPS1.

After recent changes this is no longer working. Kernel boot logs and systemd's startup messages are visible but agetty is not started.

This is regression, but to me the fix is to switch genericarm64 from build-time configure SERIAL_CONSOLES to systemd agetty generator based on detected tty's at runtime. Before recent systemd agetty refactoring, missing SERIAL_CONSOLES resulted in slowed boot when default systemd 180 second timeout was hit until systemd boot status changed from "starting" to "running" or "degraded".

Fix proposal for both slow boot and missing agetty on AMD KV260:

https://lists.yoctoproject.org/g/poky/message/13590

Additional details in

https://lists.yoctoproject.org/g/poky/message/13592

In Linaro we've been using the systemd side getty generator for a long time to support multiple devices from qemuarm64 and genericarm64 machine builds without hard coding SERIAL_CONSOLES at build time. Suppoted devices has included qemu, rpi4, synquacer, AMD KV260, AMD zcu102, rockpi4b and AVA.