Linker and Libraries Guide


ASSIGN_SECTION specifies a combination of section attributes, such as section name, type, and flags, that collectively qualify a section for assignment to a given segment. Each such set of attributes is called an entrance criterion. A section matches when the section attributes match those of an entrance criterion exactly. An ASSIGN_SECTION that does not specify any attributes matches any section that criterion is compared to.

Multiple ASSIGN_SECTION attributes are allowed for a given segment. Each ASSIGN_SECTION attribute is independent of the others. A section will be assigned to a segment if the section matches any one of the ASSIGN_SECTION definitions associated with that segment. The link-editor will not assign sections to a segment unless the segment has at least one ASSIGN_SECTION attribute.

The link-editor uses an internal list of entrance criteria to assign sections to segments. Each ASSIGN_SECTION declaration encountered in the mapfile is placed on this list, in the order encountered. The entrance criteria for the built-in segments discussed in Predefined Segments are placed on this list immediately following the final mapfile defined entry.

The entrance criterion can be given an optional name (assign_name). This name can be used in conjunction with the IS_ORDER attribute to specify the order in which input sections are placed in the output section.

To place an input section, the link-editor starts at the head of the entrance criteria list, and compares the attributes of the section to each entrance criterion in turn. The section is assigned to the segment associated with the first entrance criterion that matches the section attributes exactly. If there is no match, the section is placed at the end of the file, as is generally the case for all non-allocable sections.

ASSIGN_SECTION accepts the following.

Table 9–7 Section FLAGS Values

Flag Value 



Section is allocable 


Section is writable 


Section is executable 


Section can be larger than 2GB