After building and running
objcopy -O binary Build/aarch64/Kernel/Prekernel/Prekernel \
/media/sdcard/kernel8.img
things start booting on an actual RPi4 :^)
(Assuming the sdcard contains RPi firmware, an empty config.txt,
and no other kernel*.img files).
- .text now starts at 0x80000, where an actual (non-qemu) RPi expects
- use magic section name ".text.first" to make sure the linker script
puts the kernel entry point at the start of the .text section
- remove a few things from the x86 linker script that aren't needed
for aarch64 (yet?)
Add a dummy Arch/aarch64/boot.S that for now does nothing but
let all processor cores sleep.
For now, none of the actual Prekernel code is built for aarch64.
