The Solaris 7 installation programs have a new check box for selection of 64-bit support. The check box is active (not grayed-out) if 64-bit support is a valid option for either the hardware or the software group (metacluster) selected for installation.
Selection of 64-bit support is appropriate if the system is to be used to either develop or run applications compiled for the 64-bit SPARC instruction set. The 64-bit SPARC instruction set is currently supported on UltraSPARC systems.
Deselection of 64-bit support for an UltraSPARC system removes the ability to run or compile a 64-bit program. An UltraSPARC system with 64-bit support should execute 32-bit programs at comparable speeds (typically within a few percent) to a system running without 64-bit support.