ref: 65e0e1c3e37c966d0c18178ad8a4c54c0c0fbce9 dir: /sys/src/libc/68000/argv0.s/
GLOBL argv0(SB), $4 GLOBL _tos(SB), $4 GLOBL _privates(SB), $4 GLOBL _nprivates(SB), $4