sched_get_priority

rax	159	get the maximum priority for that policy	8 bit
rbx	policy	scheduling policy, one of: SCHED_OTHER = 0 SCHED_FIFO = 1 SCHED_RR = 2	16 bit

On return	rax
	policy/errorcode

Errorcode	c++ name	Description
22	EINVAL	Invalid argument