Does Jupiter’s U-Boot support loading extlinux? I want to customize the kernel boot parameters and rebuild a customized kernel, so having the boot menu (over the serial console) is really needed.
IDK if this is what you’re looking for, but the env partition (mmcblk0p2) is pretty much text. I’ve replaced the null bytes with newlines for easier reading, and it seems to have a line with bootargs. I haven’t tried changing anything in there yet, but I would assume you can just adjust the bootargs that way. But yeah, extlinux support would be so much better…