Preface

The capabilities of the Solaris^TM operating environment continue to expand to meet customer needs. The Solaris operating environment was designed to fully support both the 32-bit and 64-bit architectures. The Solaris operating environment provides an environment for building and running 64-bit applications that can use large files and large virtual address spaces. At the same time, the Solaris operating environment continues to provide maximum source compatibility, maximum binary compatibility, and interoperability for 32-bit applications. In fact, most of the system commands that run and have been built on the Solaris 64-bit implementation are 32-bit programs.

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Note –

This Solaris release supports systems that use the SPARC® and x86 families of processor architectures: UltraSPARC®, SPARC64, AMD64, Pentium, and Xeon EM64T. The supported systems appear in the Solaris 10 Hardware Compatibility List at http://www.sun.com/bigadmin/hcl. This document cites any implementation differences between the platform types.

In this document the term “x86” refers to 64-bit and 32-bit systems manufactured using processors compatible with the AMD64 or Intel Xeon/Pentium product families. For supported systems, see the Solaris 10 Hardware Compatibility List.

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The major differences between the 32-bit and the 64-bit application development environments are that 32-bit applications are based on the ILP32 data model, where ints, longs, and pointers are 32 bits, while 64-bit applications are based on the LP64 model, where longs and pointers are 64 bits and the other fundamental types are the same as in ILP32.

Most applications can remain as 32-bit programs with no changes required. Conversion is necessary only if the application has one or more of the following requirements:

• Needs more than 4 gigabytes of virtual address space

• Reads and interprets kernel memory through use of the libkvm library, and /dev/mem, or /dev/kmem files

• Uses /proc to debug 64-bit processes

• Uses a library that has only a 64-bit version

• Needs full 64-bit registers to do efficient 64-bit arithmetic

Specific interoperability issues can also require code changes. For example, if your application uses files that are larger than 2 gigabytes, you might want to convert the application to 64-bit.

In some cases, you might want to convert applications to 64-bit for performance reasons. For example, you might need the 64-bit registers to do efficient 64-bit arithmetic or you might want to take advantage of other performance improvements that a 64–bit instruction set provides.

Who Should Use This Book

This document is written for C and C++ developers and provides guidance on how to determine whether an application is 32-bit or 64-bit. This document provides

• A list of the similarities and differences between the 32-bit and 64-bit application environments

• An explanation of how to write code that is portable between the two environments

• A description of the tools provided by the operating system for developing 64-bit applications

How This Book Is Organized

This book is organized into the following chapters.

• Chapter 1, 64-bit Computing describes the motivation behind 64–bit computing and gives an overview of the benefits of 64–bit applications.

• Chapter 2, When to Use 64-bit explains the differences between the Solaris 32-bit and 64-bit build and runtime environments. The information is written to help the application developer determine if and when converting code to be 64-bit safe is appropriate.

• Chapter 3, Comparing 32-bit Interfaces and 64–bit Interfaces focuses on the similarities between 32-bit applications and 64-bit applications as well as the 64-bit interfaces.

• Chapter 4, Converting Applications describes how to convert current 32–bit code to 64-bit safe code and the tools available for making this process easier. The focus of this chapter is on writing portable code. The information applies to converting existing applications or writing new applications that are capable of running in both 32-bit and 64-bit environments.

• Chapter 5, The Development Environment focuses on the build environment, including headers, compilers, and libraries, as well as packaging guidelines and debugging tools.

• Chapter 6, Advanced Topics is an overview of 64–bit systems programming, the ABI, and some performance issues.

• Appendix A, Changes in Derived Types highlights many of the derived types that have changed in the 64-bit application development environment.

• Appendix B, Frequently Asked Questions (FAQs) provides answers to the most commonly asked questions about the 64-bit implementation and application development environment.

Related Books

For further reading, the following texts are recommended:

• American National Standard for Information Systems Programming Language - C, ANSI X3.159-1989

• SPARC Architecture Manual, Version 9, SPARC International

• SPARC Compliance Definition, Version 2.4, SPARC International

• Large Files in Solaris: A White Paper, Part No: 96115-001

• Solaris 10 Reference Manual

• Writing Device Drivers, Part No: 816–4854

• Sun Studio 10: C User's Guide, Part No: 819-0494-10

Accessing Sun Documentation Online

The docs.sun.com^SM Web site enables you to access Sun technical documentation online. You can browse the docs.sun.com archive or search for a specific book title or subject. The URL is http://docs.sun.com.

What Typographic Conventions Mean

The following table describes the typographic changes that are used in this book.

Table P–1 Typographic Conventions

Typeface or Symbol	Meaning	Example
AaBbCc123	The names of commands, files, and directories; on-screen computer output	Edit your .login file. Use ls -ato list all files. machine_name% you have mail.
AaBbCc123	What you type, contrasted with on-screen computer output	machine_name% su Password:
AaBbCc123	Command-line placeholder: replace with a real name or value	To delete a file, type rm filename.
AaBbCc123	Book titles, new words or new terms, or words to be emphasized.	Read Chapter 6 in User's Guide. These are called class options. Do not save changes yet.

Shell Prompts in Command Examples

The following table shows the default system prompt and superuser prompt for the C shell, Bourne shell, and Korn shell.

Table P–2 Shell Prompts

Shell	Prompt
C shell prompt	machine_name%
C shell superuser prompt	machine_name#
Bourne shell and Korn shell prompt	$
Bourne shell and Korn shell superuser prompt	#

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Note –

The term “IA-32” refers to the Intel 32–bit processor architecture. This architecture includes the Pentium, Pentium Pro, Pentium II, Pentium II Xeon, and Pentium III processors and compatible microprocessor chips made by AMD and Cyrix.

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