HelenOS sources

root/kernel/arch/amd64/src/

[..]
amd64.c asm.S bios/ boot/ context.S
cpu/ ddi/ debug/ delay.S drivers/
fpu_context.c interrupt.c kseg.c mm/ pm.c
proc/ smc.c smp/ syscall.c userspace.c
vreg.c
[..]
HelenOS homepage, sources at GitHub