For init process, pid is 1, and some other processes, when use pmap to show their mmapped file, results show like this:
0000000000000000      0K r-x--  /sbin/init
0000000000000000      0K r----  /sbin/init
0000000000000000      0K rw---  /sbin/init
0000000000000000      0K -----    [ stack ]
0000000000000000      0K rw---    [ stack ]
0000000000000000      0K r-x--  /lib/libc-2.12.2.so
0000000000000000      0K -----  /lib/libc-2.12.2.so
0000000000000000      0K r----  /lib/libc-2.12.2.so
0000000000000000      0K rw---  /lib/libc-2.12.2.so
0000000000000000      0K rw---    [ stack ]
0000000000000000      0K r-x--  /lib/ld-2.12.2.so
0000000000000000      0K rw---    [ stack ]
0000000000000000      0K rw---    [ stack ]
0000000000000000      0K r-x--    [ stack ]
0000000000000000      0K rw---  /lib/ld-2.12.2.so
0000000000000000      0K rw---    [ stack ]
0000000000000000      0K rw---    [ stack ]
ffffffffff600000      4K r----    [ anon ]
 total                4K
why this happens? all virtual address except last one start from zero and size is zero.
