enum {
PER_LINUX = 0x0000,
PER_LINUX_32BIT = 0x0000 | ADDR_LIMIT_32BIT,
PER_LINUX_FDPIC = 0x0000 | FDPIC_FUNCPTRS,
PER_SVR4 = 0x0001 | STICKY_TIMEOUTS | MMAP_PAGE_ZERO,
[...]
So this is a combination of a personality ID and flag bits. And the
only difference between PER_LINUX and PER_LINUX_32BIT is one of those
flag bits.
Nicolas