kexec_load

load a new kernel for later execution

sys_kexec_load(unsigned long entry, unsigned long nr_segments, struct kexec_segment *segments, unsigned long flags)

register	value
`rax`	246, the syscall number
`rdi`	unsigned long entry
`rsi`	unsigned long nr_segments
`rdx`	struct kexec_segment *segments
`r10`	unsigned long flags
`rax`	the return value

Then run syscall to enter the kernel.

Same syscall on other architectures