ref: 32a27378239aadb80d6d17f2cfbc9b5ba9a9b2c0 dir: /sys/src/9/bcm64/init9.s/
TEXT main(SB), 1, $8 MOV $setSB(SB), R28 /* load the SB */ MOV $boot(SB), R0 B startboot(SB)