ARM Compiler toolchain Using the Linker - ARM Information Center

10.5 Symbol visibility for BPABI models
10.5.1 See also
BPABI and SysV shared libraries and executables
Each symbol has a visibility property that can be controlled by compiler switches, a steering file,
or attributes in the source code. If the symbol is a reference, the visibility controls the definitions
that the linker can use to define the symbol. If the symbol is a definition, the visibility controls
whether the symbol can be made visible outside the current module.
The visibility options defined by the ELF specification are:
Visibility Reference Definition
STV_DEFAULT Symbol can be bound to a definition in a
shared object.
Symbol preemption is most common in System V (SysV) systems. Symbol preemption can
happen in dynamically linked library (DLL) like implementations of the Base Platform
Application Binary Interface (BPABI). The platform owner defines how this works. See the
documentation for your specific platform for more information.
Concepts
• Optimization with RW data compression on page 5-13
• Linker options for SysV models on page 10-13
• Automatic dynamic symbol table rules in the SysV memory model on page 10-15
• Addressing modes in the SysV memory model on page 10-17
• Thread local storage in the SysV memory model on page 10-18
• Related linker command-line options for the SysV memory model on page 10-19
• Linker options for bare metal and DLL-like models on page 10-21
• About symbol versioning on page 10-27.
Reference
Linker Reference:
• --keep_protected_symbols on page 2-91
• --max_visibility=type on page 2-111
• --override_visibility on page 2-115
• --use_definition_visibility on page 2-177
• EXPORT on page 3-2
• IMPORT on page 3-4
• REQUIRE on page 3-7.
Compiler Reference:
• --apcs=qualifer...qualifier on page 3-11
• --dllexport_all, --no_dllexport_all on page 3-76
• --dllimport_runtime, --no_dllimport_runtime on page 3-77
Table 10-1 Symbol visibility
Symbol can be made visible outside the module.
It can be preempted by the dynamic linker by a
definition from another module.
STV_PROTECTED Symbol must be resolved within the module. Symbol can be made visible outside the module.
It cannot be preempted at run-time by a
definition from another module.
STV_HIDDENSTV_INTERN
AL
Symbol must be resolved within the module. Symbol is not visible outside the module.
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