Why output of pmap command does not display "RSS", "Anon" and "Locked" values on RHEL-4 ?

Issue

• Why output of pmap command does not display "RSS", "Anon" and "Locked" values on RHEL-4 ?

Eg:

# pmap -x 1
1:   init [5]                                                           
Address           Kbytes     RSS    Anon  Locked Mode   Mapping
0000000000400000      36       -       -       - r-x--  init
0000000000508000       8       -       -       - rw---  init
000000000050a000     132       -       -       - rwx--    [ anon ]
0000002a95556000       4       -       -       - rw---    [ anon ]
0000002a95573000       8       -       -       - rw---    [ anon ]
0000003e9d300000      84       -       -       - r-x--  ld-2.3.4.so
0000003e9d414000       4       -       -       - r----  ld-2.3.4.so
0000003e9d415000       4       -       -       - rw---  ld-2.3.4.so
0000003e9d500000    1212       -       -       - r-x--  libc-2.3.4.so
0000003e9d62f000    1024       -       -       - -----  libc-2.3.4.so
0000003e9d72f000      12       -       -       - r----  libc-2.3.4.so
0000003e9d732000       8       -       -       - rw---  libc-2.3.4.so
0000003e9d734000      20       -       -       - rw---    [ anon ]
0000003e9d800000      56       -       -       - r-x--  libsepol.so.1
0000003e9d80e000    1020       -       -       - -----  libsepol.so.1
0000003e9d90d000       4       -       -       - rw---  libsepol.so.1
0000003e9d90e000      32       -       -       - rw---    [ anon ]
0000003e9e800000      56       -       -       - r-x--  libselinux.so.1
0000003e9e80e000    1024       -       -       - -----  libselinux.so.1
0000003e9e90e000       4       -       -       - rw---  libselinux.so.1
0000003e9e90f000       4       -       -       - rw---    [ anon ]
0000007fbfffc000      16       -       -       - rw---    [ stack ]
ffffffffff600000       4       -       -       - r-x--    [ anon ]
----------------  ------  ------  ------  ------
total kB            4776       -       -       -

• Why headers are different in the output of pmap command on RHEL-4 and RHEL-5 ?

Eg:

# cat /etc/redhat-release 
Red Hat Enterprise Linux AS release 4 (Nahant Update 9)

# pmap -x 1 |grep Address
Address           Kbytes     RSS    Anon  Locked Mode   Mapping

# cat /etc/redhat-release 
Red Hat Enterprise Linux Server release 5.9 (Tikanga)

# pmap -x 1 |grep Address
Address           Kbytes     RSS   Dirty Mode   Mapping