zero_fd          1568 gc/os_dep.c      static int zero_fd;
zero_fd          1591 gc/os_dep.c    	  zero_fd = open("/dev/zero", O_RDONLY);
zero_fd          1592 gc/os_dep.c    	  fcntl(zero_fd, F_SETFD, FD_CLOEXEC);
zero_fd          1599 gc/os_dep.c    		  GC_MMAP_FLAGS | OPT_MAP_ANON, zero_fd, 0/* offset */);
zero_fd          1863 gc/os_dep.c    		      zero_fd, 0/* offset */);