ref: 2f4c39ec2bf7a5eb84ed1a7c810a0a85b2e47cd0 dir: /sys/src/ape/lib/ap/386/tas.s/
TEXT tas(SB),$0 MOVL $0xdeadead,AX MOVL l+0(FP),BX XCHGL AX,(BX) RET