ref: bdcf2a2f5fb2ef0ccda329d0f3f8338fb5009e9c dir: /sys/src/libc/alpha/argv0.s/
GLOBL argv0(SB), $4 GLOBL _tos(SB), $4 GLOBL _privates(SB), $4 GLOBL _nprivates(SB), $4