You probably run applications in the 64-bit Solaris environment no differently than in the 32-bit Solaris environment.
A user's PATH environment variable does not need to change to use a 64-bit Solaris system. Although most system utilities remain 32-bit applications, some are available in 64-bit versions. The 64-bit command versions are automatically invoked by a command wrapper program that transparently starts the correct version of the command based upon the capabilities of the running system.
Other issues to keep in mind when running applications in the 64-bit Solaris operating environment:
If a 32-bit application reads kernel memory, it needs to be compiled as a 64-bit program because the kernel is now a 64-bit program.
If a 32-bit program uses the /proc file system to look at other processes, it may need to be converted to a 64-bit program to understand the extended capabilities of 64-bit processes.
If you intend to run 64-bit applications that require large virtual address spaces, you may need to add more swap space to the system.
System administrators should be certain that they have the correct device drivers available for their 64-bit Solaris systems by following these steps:
Verify whether the UltraSPARC system needs a firmware upgrade to boot the 64-bit Solaris kernel. See your hardware manufacturer's documentation to determine whether your UltraSPARC system needs a firmware upgrade.
Select the 64-bit Solaris packages during installation.
Boot the 64-bit Solaris operating environment.
Another important administration issue is making sure your third-party device drivers are available in 64-bit versions; otherwise you probably won't be able to run the 64-bit Solaris environment until they are available in 64-bit versions.
If you are running 64-bit applications, you may need to customize your LD_LIBRARY_PATH environment variable as follows:
Set the new environment variable, LD_LIBRARY_PATH_64, like LD_LIBRARY_PATH, except that it can only be referenced by 64-bit applications.
Set the LD_LIBRARY_PATH variable to allow applications to reference a combination of both 32-bit and 64-bit libraries.