HP-UX Linker and Libraries User's Guide

• At most one section_type can be specified in a mapping directive.
• If a section flag is preceded by an exclamation mark (!), it indicates that the flag must not be
set to meet the entrance criteria. If you do not specify section_flags, the flag can have
any value to meet the entrance criteria.
S1 : ?X;
The linker maps all executable sections onto segment S1.
• The section_name attribute indicates that the linker must map the input sections with the specified
name onto the named segment.
text : .rodata;
• An input section can satisfy more than one entrance criterion.
S1 : $PROGBITS;
S2 : $PROGBITS;
In this case, all sections with section type $PROGBITS are mapped onto segment S1 as the
first rule takes precedence.
• An AND relationship exists between attributes specified on the same line. An OR relationship
exists between attributes specified for the same segment that span more than one line.
◦ Example 1: All sections with section_type $PROGBITS and section_flags AX (allocatable
and executable) are mapped onto the text segment. text : $PROGBITS ?AX;
◦ Example 2: text : $PROGBITS ?AX; text : .rodata; In this case, the linker maps
a section onto the text segment if: Its section_type is $PROGBITS and
section_flags is AX. (or) Its section_name is .rodata.
Internal Map Structure
The linker use a default map structure corresponding to the default mapfile. When you use the
mapfile option with the ld command, the linker appends the default mapfile to the end of your
user-specified mapfile. (You can override the default mapfile by using the +nodefaultmap option.)
Placement of Segments in an Executable
As it processes each segment declaration in the mapfile, the linker compares it with the existing
list of segment declarations as follows:
• If the segment does not exist already, but another with the same segment_type exists, the linker
adds the segment after all of the existing segments with the same segment_type.
• If no segment with the same segment_type exists, the linker adds the new segment to the list
to maintain the following order based on segment_type:
◦ LOAD
◦ HP_TLS
◦ NOTE
◦ NONSEGMENT
• If segments of same type already exists, the linker adds the new segment after the last segment
with the same type.
Mapping Input Sections to Segments
As each section mapping directive in a mapfile is read in, the linker creates a new entrance criteria
and appends it to the existing list of entrance criteria. It applies the entrance criteria in the order
198 Using Mapfiles