ref: aacdabd9f8ceb3f9e64c492c5be3de8ddf0f77c2 dir: /sys/src/libc/68000/argv0.s/
GLOBL argv0(SB), $4 GLOBL _tos(SB), $4 GLOBL _privates(SB), $4 GLOBL _nprivates(SB), $4