Im looking for a solution to install Ubuntu on a USB-Stick but make it bootable on Amd64 (Intel and AMD Processors) as well as Arm64 (Eg. Raspberry Pi x64).
Is there a solution to pack eg 2 Kernels, one for amd64 and one for arm64, and have a "smart bootloader" to detect which one to read at boot?
Also super creative solutions welcome, is not for production purposes, just for testing-ease
Old RPi computers only booted from SD cards. I don't know newer RPi hardware and BIOSes, and I have not used ARM system for any other kind of computer.
So I don't know enough of booting of ARM computers. But the following method might work in USB drives and/or SD cards, if the ARM boot does not interfere with UEFI mode of PC computers:
Flash from a (compressed) image file for ARM (for example RPi) to the target drive (USB pendrive or SD card). Check that it works.
Edit the partition table to get enough drive space for Ubuntu's amd64 system (maybe around half of the total drive space). I suggest that you prepare for UEFI mode with a small partition (maybe 512 MB) with the FAT32 file system and the EFI flag, and make the rest of the unallocated space into a partition with the ext4 file system.
Then (when booted from the Ubuntu amd64 live system), install Ubuntu into the target drive (the ext4 file system) that you created for that purpose.
If there is an UEFI mode Linux or Windows system in the computer, where you install into the target drive, there might be a problem, so you might need to remove, disconnect or otherwise disable the internal drive in order to get the EFI system installed into the target drive (not automatically put into the internal drive). This happens when using the installer Ubiquity used by standard Ubuntu Desktop and most of the Ubuntu family flavours. But newer Lubuntu uses the Calamares installer, which is not affected by that bug, so if you cannot or don't want to disable your internal drive, install Lubuntu 20.04.4 LTS or 22.04 LTS.
Finally, please share your results, whatever they are (good or bad).
