I have a Raspberry Pi 400 booting Ubuntu from a USB/SSD.
I was wondering if there is a way to boot from same pendrive but on a PC, of course with a corresponding Ubuntu for x86-64 installed on a different partition on that SSD.
With a third partition for data, it would be the best of both worlds, using the Pi for easy portability and a PC when requiring more "power"
Anyone has experimented with such thing?
Check out BerryBoot, that might help with that.
If that doesn't work, see answer https://raspberrypi.stackexchange.com/a/38888.
No. You could (I believe this is what something like berryboot probably does; I haven't used it) load a minimal root fs, possibly from an initramfs, present the user with options, and then switch the root filesystem (which is what initramfs kernels always do), but obviously there is a bit of work involved. Alternately, you could write your own bootloader code, but this is even more work, and may require some proprietary knowledge (I'm not sure).
Also see https://superuser.com/a/1520139/1167517, which details how to boot from selected partition on a Raspberry PI 3.
Obvious disclaimer: Playing with boot files is highly dangerous and can cause a non bootable drive. Make sure to backup files from SD card before doing this.
