Relocation (computing): Difference between revisions

Revision as of 18:56, 20 April 2025

Revision as of 17:11, 12 May 2025

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A [[linker (computing)|linker]] usually performs relocation in conjunction with ''symbol resolution'', the process of searching files and libraries to replace symbolic references or names of [[library (computer science)|libraries]] with actual usable addresses in [[primary storage|memory]] before running a program.

Relocation is typically done by the linker at [[link time]], but it can also be done at [[load time]] by a relocating [[loader (computing)|loader]], or at [[run time (program lifecycle phase)|run time]] by the running program [[self-relocation|itself]].<!--[[User:Kvng/RTH]]-->

== Segmentation ==

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== Relocation table ==

The relocation table is a list of [[pointer (computer programming)|pointer]]saddresses created by the translator (a [[compiler]] or [[Assembler (computer programming)#Assembler|assembler]]) and stored in the object or executable file. Each entry in the table, or "fixup", is a [[pointer (computer programming)|pointer]] toreferences an absolute address in the object code that must be changed when the loader relocates the program so that it will refer to the correct ___location. FixupsEntries in the relocation table are known as ''fixups'' and are designed to support relocation of the program as a complete unit. In some cases, each fixup in the table is itself relative to a base address of zero, so the fixups themselves must be changed as the loader moves through the table.<ref name="Levine_1999_CH1_CH3"/>

In some architectures a fixup that crosses certain boundaries (such as a segment boundary) or that is not aligned on a word boundary is illegal and flagged as an error by the linker.<ref name="Borland_2007"/><!--[[User:Kvng/RTH]]-->

=== DOS and 16-bit Windows ===