Solaris, by default, loads a 64-bit kernel during boot up, if the hardware supports it.

If, for whatever reason, you need to load Solaris in 32-bit mode, the following commands can be used to switch between the 32-bit and 64-bit kernels.

To boot into a 32-bit kernel:

# eeprom boot-file="kernel/unix"

To boot into a 64-bit kernel on Solaris x86:

# eeprom boot-file="kernel/amd64/unix"

To boot into a 64-bit kernel on Solaris SPARC:

# eeprom boot-file="kernel/sparcv9/unix"

To restore the default auto detected boot behavior:

# eeprom boot-file=""

If you are on the OBP (Open Boot PROM), you can use the setenv command to set the ‘boot-file’ parameter. OBP is only available on SPARC Hardware.

OK> setenv  boot-file  kernel/unix

OK> setenv  boot-file  kernel/sparcv9/unix

A reboot is necessary to switch to the new kernel.