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Nisha Sethi, Lovely Professional University Unit 8: Introduction to Linking and Loading

Unit 8: Introduction to Linking and Loading Notes

CONTENTS

Objectives
Introduction
8.1 Loader Schemes
8.1.1 “Compile and Go” Loader
8.1.2 General Loader Scheme

8.1.3 Absolute Loaders
8.1.4 Subroutine Linkage
8.1.5 Relocating Loaders

8.1.6 Direct Linking Loaders
8.2 Other Loader Schemes
8.2.1 Binders
8.2.2 Linkers
8.2.3 Loaders

8.2.4 Overlay Structures and Dynamic Loading
8.2.5 Dynamic Binders
8.3 Summary

8.4 Keywords
8.5 Review Questions
8.6 Further Readings

Objectives

After studying this unit, you will be able to:

 Understand the concepts of linking and loading
 Study various loader schemes such as compile and go loaders, general loader scheme, etc.

Introduction

Loader is defined as a utility program which considers object code as input organizes it for
implementation and loads the executable code into the memory. Thus, loader, is in fact accountable
for initiating the implementation process.
The loader is accountable for the activities like allocation, linking, relocation and loading:

1. It assigns the space for program in the memory, by computing the size of the program.
This activity is known as allocation.
2. It solves the symbolic references (code/data) among the object modules by allocating all
the user subroutine and library subroutine addresses. This activity is known as linking.

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