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Solaris 64-bit Developer's Guide
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Document Information


1.  64-bit Computing

2.  When to Use 64-bit

Major Features

Large Virtual Address Space

Large Files

64-bit Arithmetic

System Limitations Removed

Interoperability Issues

Kernel Memory Readers

/proc Restrictions

64-bit Libraries

Estimating the Effort of Conversion

3.  Comparing 32-bit Interfaces and 64-bit Interfaces

4.  Converting Applications

5.  The Development Environment

6.  Advanced Topics

A.  Changes in Derived Types

B.  Frequently Asked Questions (FAQs)


Chapter 2

When to Use 64-bit

For application developers, the major difference between the Solaris 64-bit and 32-bit operating environments is the C data type model used. The 64–bit version uses the LP64 model where longs and pointers are 64–bits. All other fundamental data types remain the same as in the 32-bit implementation, which is based on the ILP32 model. In the ILP32 model, ints, longs, and pointers are 32-bit quantities. These models are explained in greater detail in Chapter 3, Comparing 32-bit Interfaces and 64-bit Interfaces.

Few applications really require conversion. Most applications can remain as 32-bit applications and still run on the 64-bit operating system without requiring any code changes or recompilation. In fact, 32-bit applications that do not require 64-bit capabilities should probably remain 32-bit to maximize portability.

You might want to convert applications with the following characteristics:

You might need to convert applications with these characteristics:

Some specific interoperability issues require code changes. Similarly, if your application uses files that are larger than 2 gigabytes, consider conversion to a 64-bit application instead of using the large file APIs directly.

These items are explained further in the sections that follow.