10.3.4 Input/Output Section Map

The section map is the heart of the linker script. It defines how input sections are mapped to output sections. Note that input sections are portions of an application that are defined in source code, while output sections are created by the linker. Generally, several input sections may be combined into a single output section.

For example, suppose that an application is comprised of five different functions, and each function is defined in a separate source file. Together, these source files will produce five input sections. The linker will combine these input sections into a single output section. Only the output section has an absolute address.

If any input or output sections are empty, there is no penalty or storage cost for the linked application. Most applications will use only a few of the many sections that appear in the section map.