64-bit Mode Run Time Differences

Applications compiled and linked in 64-bit mode use a run-time dynamic loading model similar to other SVR4 systems. There are two main areas where program startup changes in 64-bit mode:

Dynamic path searching for shared libraries.
Symbol searching in dependent libraries.

It is recommended that you use the standard SVR4 linking option (+std), which is on by default when linking 64-bit applications. There may be circumstances while you transition, that you need 32-bit compatible linking behavior. The 64-bit linker provides the +compat option to force the linker to use 32-bit linking and dynamic loading behavior.

The following table summarizes the dynamic loader differences between 32-bit and 64-bit mode:

Linker and Loader Functions	32-bit Mode Behavior	64-bit Mode Behavior
`+s` and `+b` `path_list` ordering	Ordering is significant.	Ordering is insignificant by default. Use `+compat` to enforce ordering.
Symbol searching in dependent libraries	Depth-first search order.	Breadth-first search order. Use `+compat` to enforce depth first ordering.
Run time path environment variables	No run time environment variables by default. If `+s` is specified, then `SHLIB_PATH` is available.	`LD_LIBRARY_PATH` and `SHLIB_PATH` are available. Use `+noenv` or `+compat` to turn off run-time path environment variables.
`+b` `path_list` and `-L` `directories` interaction	`-L` `directories` recorded as absolute paths in executables.	`-L` `directories` are not recorded in executables. Add all directories specified in `-L` to `+b` `path_list`.

For more information on transition issues, see HP-UX 64-bit Porting and Transition Guide.

64-bit Mode Run Time Differences

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