ref: 1c08b2c8260b55aeadc7fbe8cb8f59a18a22ed45 dir: /sys/src/libc/68000/argv0.s/
GLOBL argv0(SB), $4 GLOBL _tos(SB), $4 GLOBL _privates(SB), $4 GLOBL _nprivates(SB), $4