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Controlling how the linker searches for the ARM standard libraries

By default, the linker searches for the ARM standard libraries in ../lib, relative to the location of the armlink executable. You can also control how the linker searches for the ARM standard libraries with the --libpath command-line option.

Some libraries are stored in subdirectories. A library might be added in assembly code or by a linker script from a particular subdirectory. For such a library , the names of subdirectories are placed in each object by using a symbol of the form Lib$$Request$$sub_dir_name. You must specify the linker command-line option --force_scanlib to inform the compiler to look in all subdirectories for system libraries.

Using the --libpath command-line option

Use the --libpath command-line option with a comma-separated list of parent directories. This list must end with the parent directory of the ARM library directories armlib and cpplib.

The linker searches subdirectories given by the symbol Lib$$Request$$sub_dir_name, if you include the path separator character on the end of the library path:

  • \ on Windows.

  • / on Red Hat Linux.

For example, for --libpath=mylibs\ and the symbol Lib$$Request$$armlib the linker searches the directories:

mylibs
mylibs\armlib

The sequential nature of the search ensures that the linker chooses the library that appears earlier in the list if two or more libraries define the same symbol.

Library search order

The linker searches for libraries in the following order:

  1. Relative to the current path.

  2. At the location specified with the command-line option --libpath.

  3. At the location specified in ../lib.

How the linker selects ARM library variants

The ARM Compiler toolchain includes a number of variants of each of the libraries, that are built using different build options. For example, architecture versions and instruction set. The variant of the ARM library is coded into the library name. The linker must select the best-suited variant from each of the directories identified during the library search.

The linker accumulates the attributes of each input object and then selects the library variant best suited to those attributes. If more than one of the selected libraries are equally suited, the linker retains the first library selected and rejects all others.

See also

Concepts
Reference

armlink Reference Guide:

ARM C and C++ Libraries and Floating-Point Support User Guide:

ARM C and C++ Libraries and Floating-Point Support Reference Guide: