The 64-bit Solaris operating environment is a complete 32-bit and 64-bit application and development environment supported by a 64-bit operating system. This permits maximum compatibility and interoperability for existing applications, both source and binary. At the same time, the 64-bit Solaris operating environment overcomes the limitations of the 32-bit system, most notably by supporting a 64-bit virtual address space and removing other 32-bit system limitations.
The key limitations overcome by the 64-bit Solaris operating environment are the following:
Full 64-bit integer arithmetic for 64-bit applications. Though 64-bit arithmetic has been available in all Solaris 2.x releases, the 64-bit implementation now uses full 64-bit machine registers for integer operations and parameter passing. This allows an application to take full advantage of the capabilities of the 64-bit CPU hardware.
Greater than 2 Gbytes tmpfs on the 64-bit system.
Greater than 2 Gbytes per swap device on the 64-bit system.
The compatibility and interoperability in the 64-bit Solaris operating environment is so complete that there is no noticeable difference. Existing applications just work and PATH settings remain unchanged.
The new isainfo program helps determine whether you are running on a 32-bit or 64-bit system. isainfo prints information about all the supported Instruction Set Architectures (ISA) of the running system.
Finally, there is the option of booting either the 32-bit or 64-bit Solaris operating environment on UltraSPARC machines.