ref: 6b2d1f0186f2e38a3b0cd6a19b5980dccb045c3c dir: /sys/src/libc/alpha/argv0.s/
GLOBL argv0(SB), $4 GLOBL _tos(SB), $4 GLOBL _privates(SB), $4 GLOBL _nprivates(SB), $4