There are actually three page sizes here:

1. The MMU page size
2. The OS page size (PAGE_SIZE)
3. The linker page size

You cannot change #1 if you want to support older HPs (320, 350, 370) which
have the HP MMU.

You really don't want to change #2 unless you want to fix the pmap module.

Changing #3 is reasonably transparent (modulo all the things people have
already brought up).  We needed to do this for the hp800 (2k page size)
and hp700 (4k page size) so we could run the same binaries on both.