64bit & 32bit mode on an E450!

Yes the default mode on Solaris 7 & later on any 64bit processor (except the Ultra 140/170's) is to boot a 64 bit kernel. The only reason that I'm aware of to need to boot a 32 bit kernel (via "boot disk /platform/sun4u/kernel/unix) is if you have something that only has a 32 bit driver. Applications will run in 32 bit or 64 bit mode depending on how they were built or a 64 bit kernel.

Here are the answers to questions 1 and 2:

1. To determine if a Solaris 7 system is running in 32-bit or 64-bit mode, run:

# isainfo -v
64-bit sparcv9 applications
32-bit sparc applications

If both of the above lines are displayed, then the system is running in 64-bit mode.  If only the second line referring to 32-bit is displayed, then the system is running in 32-bit mode.

2. To change modes, enter the following at the "ok>" prompt:

To set up booting 32-bit mode:
      setenv boot-file kernel/unix

To set up booting 64-bit mode:
   setenv boot-file kernel/sparcv9/unix