Hi Kuan-Wei, On Fri, 19 Dec 2025 at 04:06, Kuan-Wei Chiu <[email protected]> wrote: > > Add support for the QEMU 'virt' machine on the m68k architecture. This > board emulates a generic machine based on the Motorola 68040 CPU > equipped with Goldfish virtual peripherals.
Since I already have this setup working and able to boot linux I will add some input: - The virt machine can use any supported CPU type, even 000 without mmu, you should really handle that. - m68k linux for mmu machines uses "bootinfo" that is a structure after the kernel image that the bootloader prepares so linux can work out what CPU etc is present. QEMU does this as well but it will be after the u-boot image now, so to boot linux you must save it before it gets destroyed and when the kernel is loaded copy it to after the kernel. I use ELF images to boot linux. I have a hack in bootelf to put the bootinfo in place just before jumping to the entry point. - Since QEMU gives you the bootinfo and you need to parse it to work out how much to save either way you should use it to detect the selected CPU in u-boot. If the code is built for 000 it will run on anything and just needs to handle the differences in the caches. In my setup I fixup the cpu compatible string in u-boot's devicetree and then use that to work out what cache function to call for the current CPU. Glad to see I'm not alone in messing around with this. :) Cheers, Daniel
