linkerscripts

A linker script is a configuration file used by the GNU linker (ld) and other linkers to control how the input sections of object files are combined into the output executable. Linker scripts provide a way to specify the memory map of the target system and the placement of various sections, such as code, data, and BSS, within that memory map. This is particularly important in embedded systems where memory organization can be critical for performance and functionality.

The linker script essentially defines the layout of the final executable. It specifies the starting address and size of different memory regions, such as ROM and RAM. Then, it dictates which input sections from the object files should be placed into these memory regions. For example, a linker script can ensure that read-only code sections are placed in ROM, while initialized data sections are placed in RAM at a specific address. Uninitialized data sections (BSS) are also handled, typically allocated in RAM.

Common directives within a linker script include SECTIONS, which is the main command for defining section placement, and MEMORY, which defines available memory regions. Symbols can also be defined or manipulated within a linker script, allowing for precise control over addresses and data structures. Understanding and writing linker scripts is a fundamental skill for embedded software development, as it allows developers to tailor the executable's memory layout to the specific requirements of the hardware. This can impact boot times, memory usage, and the overall behavior of the program.