How to convert from 64-bit to 32-bit and vice versa ?

To truly change the kernel to 64-bit, you need to be at least 5.1 oslevel. The
means to change to a 64-bit kernel are:

From 32-bit to 64-bit:
     ln -sf /usr/lib/boot/unix_64 /unix
     ln -sf /usr/lib/boot/unix_64 /usr/lib/boot/unix
     bosboot -ad /dev/ipldevice
     shutdown -Fr
     bootinfo -K (should now be 64)

To change the kernel back to 32-bit:

From 64-bit to 32-bit:
     ln -sf /usr/lib/boot/unix_mp /unix
     ln -sf /usr/lib/boot/unix_mp /usr/lib/boot/unix
     bosboot -ad /dev/ipldevice
     shutdown -Fr
     bootinfo -K (should now be 32)