For now, this can only query microseconds since boot.
Use this to print a timestamp every second. This busy-loops
until a second has passed. This might be a good first use of
interrupts soon.
qemu used to not implement this timer at some point, but
it seems to work fine even in qemu now (qemu v 5.2.0).
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?)
This moves Kernel/Prekernel/linker.ld unchanged to
Kernel/Prekernel/Arch/aarch64 and Kernel/Prekernel/Arch/x86.
The aarch64 will change in a future commit.
No behavior change.
As a demo, query the firmware version. `Meta/serenity.sh gdb aarch64`
can be used to observe that qemu puts 0x548E1 in x0 in response
to this mailbox message.
Needed for functions that have local variables.
In time we need to share this between aarch64 and intel, but while
we figure out what exactly the aarch64 Prekernel should do, let's
duplicate this.
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.
