ARM Compiler toolchain Using the Linker - ARM Information Center

Image structure and generation
4.23 How the linker performs library searching, selection, and scanning
4.23.1 See also
The linker always searches user libraries before the ARM libraries. If you specify the
--no_scanlib command-line option, the linker does not search for the default ARM libraries and
uses only those libraries that are specified in the input file list to resolve references.
The linker creates an internal list of libraries as follows:
1. Any libraries explicitly specified in the input file list are added to the list.
2. The user-specified search path is examined to identify ARM standard libraries to satisfy
requests embedded in the input objects.
The best-suited library variants are chosen from the searched directories and their
subdirectories. Libraries supplied by ARM have multiple variants that are named
according to the attributes of their members.
Be aware of the following differences between the way the linker adds object files to the image
and the way it adds libraries to the image:
• Each object file in the input list is added to the output image unconditionally, whether or
not anything refers to it. At least one object must be specified.
• A member from a library is included in the output only if:
— an object file or an already-included library member makes a non-weak reference
to it
— the linker is explicitly instructed to add it.
Note
If a library member is explicitly requested in the input file list, the member is loaded even
if it does not resolve any current references. In this case, an explicitly requested member
is treated as if it is an ordinary object.
Unresolved references to weak symbols do not cause library members to be loaded.
Tasks
• About weak references and definitions on page 4-32
• Controlling how the linker searches for the ARM standard libraries on page 4-36.
Reference
Linker Reference:
• --keep=section_id on page 2-89
• --remove, --no_remove on page 2-134
• --scanlib, --no_scanlib on page 2-141.
ARM DUI 0474C Copyright © 2010-2011 ARM. All rights reserved. 4-35
ID080411 Non-Confidential