After the 64–bit Solaris release is installed on an UltraSPARC system, the 64–bit kernel will be booted automatically unless any of the following conditions are true:
A FLASH PROM upgrade might be required on an UltraSPARC system before it can successfully boot the 64–bit kernel. Refer to your hardware manufacturer's documentation to determine whether your UltraSPARC system requires a firmware upgrade.
The Open Boot PROM boot-file parameter is set to kernel/unix. If booting the 64–bit kernel fails and this parameter is set, unset it, and reboot the system.
On some UltraSPARC systems, the 64-bit Solaris kernel is not booted by default, even when the system is completely installed with all the 64-bit Solaris components and the correct firmware is installed. Without booting the 64-bit Solaris kernel, 64-bit applications are unable to run.
To find out more about this issue, and how to enable booting the 64-bit Solaris kernel by default, see boot(1M).
You can always discover which Solaris kernel the system is currently running by using the isainfo -kv command.
$ isainfo -kv 64-bit sparcv9 kernel modules
This output means the system is running the 64–bit Solaris kernel.
You cannot boot the 64-bit Solaris operating environment on a 32-bit Solaris system.