(11-07-2019, 02:51 AM)mfritsche Wrote: Next stupid question:
I see that extlinux.conf defines a boot menu. Is the menu only available via serial console?
Yes.
Hopefully this can change as the platform matures (u-boot can draw to framebuffers and listen to USB keyboards but it requires drivers and these don't exist just yet) but at present you need a serial port to interact with the boot menu.
A simple approach is to put your boot partition on an SD card since if you need to change kernel you can eject the card, boot from a eMMC and edit extlinux.conf .