chayleaf , 8 months ago

1. Does your board support UEFI? Have you flashed it, if necessary? If not, your only option is board-specific image with board-specific U-Boot. Still, you may have some luck with mainline kernel after you flash that image.
2. Assuming you’ve flashed UEFI and know how to work with it, you should IMO install mainline images whenever possible, as those will always have the Linux kernel with latest security patches (you shouldn’t use LTS kernel before you’ve verified the very latest kernel version, unless your board is like 10 years old)
3. However, mainline Linux is often missing certain features on certain boards. In that case, you may have to either load some dtb/.dtbo files (it’s a way to specify hardware information at boot time), or, worst case, compile your own kernel with certain patches pulled from developers working on mainlining your board
4. If you don’t want to deal with all that, you can use premade images for your board. They will typically have an old kernel, but nonetheless it should Just Work™. You may still have to pick some .dtbs manually if your hardware is configurable enough (e.g. BPI-R3 has SD/EMMC switch, you can’t use both at the same time, and you have to pick the specific .dtb file depending on what you use)