COMPSCI 61C Lecture Notes - Lecture 13: System Call, Source Code, Data Segment
23 Feb 2017
School
Department
Course
Professor
Document Summary
Input: object code les, information tables (e. g. , foo. o, libc. o for mips) Combines several object les into a single executable ( linking ) Useful for recompiling only small edited portions of code. Changes to one le do not require recompilation of the whole program. Old name link editor from editing the links in jump and link instructions. Steps: take text segment from each . o le and put them together, take data segment from each . o le, put them together, and concatenate this onto end of text segments, resolve references. Loads and stores to variables in static area, relative to global pointer. Linker assumes rst word of rst text segment is at address 0x04000000. Absolute address of each label to be jumped to (internal or external) and each piece of data being referenced. Search for reference (data or label) in all user symbol tables. Once absolute address is determined, ll in the machine code appropriately.
