ref: 9ad75b63d6b975b3ae6a69bc3c0a4638b4b18fbc dir: /sys/src/libc/amd64/argv0.s/
GLOBL argv0(SB), $8 GLOBL _tos(SB), $8 GLOBL _privates(SB), $8 GLOBL _nprivates(SB), $4