Sections

A section of an object file is the smallest unit of relocation and must be a contiguous block of memory. A section is identified by a starting address and a size. Information describing all the sections in a file is stored in section headers at the start of the file. Sections in an ld input object file are called input sections; sections in a file created by ld are called output sections. Sections from input files are combined to form output sections that contain executable text, data, or a mixture of both. The link editor performs allocation, that is, the setting aside of some portion of the virtual address space for a section. Although there may be holes or gaps between input sections and between output sections, storage is allocated contiguously within each output section and may not overlap a hole in memory.