User's Manual

When is -B restricted most useful? Consider a program that creates duplicate symbol definitions
by either of these methods:
• The program uses shl_load with the BIND_FIRST flag to load a library that contains symbol
definitions that are already defined in a library that was loaded at program startup.
• The program calls shl_definesym to define a symbol that is already defined in a library
that was loaded at program startup.
If such a program is linked with -B immediate, references to symbols are bound at program
startup, regardless of whether duplicate symbols are created later by shl_load or
shl_definesym.
But what happens when, to take advantage of the performance benefits of deferred binding, the
same program is linked with -B deferred? If a duplicate, more visible symbol definition is
created prior to referencing the symbol, it binds to the more visible definition, and the program
may run incorrectly. In such cases, -B restricted is useful, because symbols bind the same
way as they do with -B immediate, but the actual binding is still deferred.
Direct Shared Library Binding with -B direct
The linker also supports direct binding, which creates a direct link between symbol references and
shared libraries by recording the name of the resolved shared library during symbol resolution.
This information is used during runtime to quickly resolve symbols without searching through all
currently-loaded libraries.
The -B direct option implicitly turns on symbolic binding and disables dependent shared library
processing.
Direct binding can be disabled during runtime by setting the LD_NODIRECTBIND environment
variable.
Shared Library Binding with -B group
Group binding marks the shared library so that it behaves as if loaded with RTLD_GROUP flag to
dlopen(). This does not affect the dependent shared libraries.
NOTE: You can use the libraries built with the -B group option only with the dld.sl in version
B.11.37 or later.
Lazydirect Shared Library Binding with -B lazydirect
Lazydirect binding only records direct bind information to shared libraries that are marked for lazy
loading. See +[no]lazyload.
Shared Library Binding with -B nodelete
Nodelete binding marks the shared library so that an explicit unload using dlclose or shl_load
returns success silently without detaching the shared library from the process. Subsequently, the
shared library handle is valid only for shl_findsym. It stays invalid for dlsym, dlclose, and
shl_unload until the next explicit load using shl_load or dlopen.
NOTE: You can use the libraries built with the -B nodelete option only with the dld.sl in
version B.11.37 or later.
-B nodirect
Nodirect binding precludes direct binding. Only a "direct hint" is recorded for references to libraries
marked for lazy loading. This is the default behavior.
Using Linker Commands 33