I got my hands on an AIX LPAR and tinkered with it a bit.

echo `lsattr -El sys0 -a systemid | cut -f 2 -d\ ` `uname -L` | sed -e 's/ /,/g'

Translated roughly to English: echo the system id, taking the second field, space, LPAR partition ID, replacing spaces with commas.

This works for me on an LPAR, but I have no way to try it on a physical AIX server.

    - Tim.