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Oracle Solaris 11.1 Linkers and Libraries Guide     Oracle Solaris 11.1 Information Library
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Document Information

Preface

Part I Using the Link-Editor and Runtime Linker

1.  Introduction to the Oracle Solaris Link Editors

2.  Link-Editor

3.  Runtime Linker

Shared Object Dependencies

Locating Shared Object Dependencies

Directories Searched by the Runtime Linker

Configuring the Default Search Paths

Dynamic String Tokens

Relocation Processing

Relocation Symbol Lookup

Default Symbol Lookup

Runtime Interposition

When Relocations Are Performed

Relocation Errors

Loading Additional Objects

Lazy Loading of Dynamic Dependencies

Providing an Alternative to dlopen()

Initialization and Termination Routines

Initialization and Termination Order

Security

Runtime Linking Programming Interface

Loading Additional Objects

Relocation Processing

Symbol Lookup

Obtaining New Symbols

Testing for Functionality

Using Interposition

Debugging Aids

Debugging Facility

Debugger Module

4.  Shared Objects

Part II Quick Reference

5.  Link-Editor Quick Reference

Part III Advanced Topics

6.  Direct Bindings

7.  Building Objects to Optimize System Performance

8.  Mapfiles

9.  Interfaces and Versioning

10.  Establishing Dependencies with Dynamic String Tokens

11.  Extensibility Mechanisms

Part IV ELF Application Binary Interface

12.  Object File Format

13.  Program Loading and Dynamic Linking

14.  Thread-Local Storage

Part V Appendices

A.  Linker and Libraries Updates and New Features

B.  System V Release 4 (Version 1) Mapfiles

Index

Chapter 3

Runtime Linker

As part of the initialization and execution of a dynamic executable, an interpreter is called to complete the binding of the application to its dependencies. In the Oracle Solaris OS, this interpreter is referred to as the runtime linker.

During the link-editing of a dynamic executable, a special .interp section, together with an associated program header, are created. This section contains a path name specifying the program's interpreter. The default name supplied by the link-editor is the name of the runtime linker: /usr/lib/ld.so.1 for a 32–bit executable and /usr/lib/64/ld.so.1 for a 64–bit executable.


Note - ld.so.1 is a special case of a shared object. Here, a version number of 1 is used. However, later Oracle Solaris OS releases might provide higher version numbers.


During the process of executing a dynamic object, the kernel loads the file and reads the program header information. See Program Header. From this information, the kernel locates the name of the required interpreter. The kernel loads, and transfers control to this interpreter, passing sufficient information to enable the interpreter to continue executing the application.

In addition to initializing an application, the runtime linker provides services that enable the application to extend its address space. This process involves loading additional objects and binding to symbols provided by these objects.

The runtime linker performs the following actions.