64-Bit Windows

作者: Jeffrey Richter, Christophe Nasarre 出处:Microsoft Press 　2008-07-25 18:20　   砖    好    评论  条 　进入论坛

阅读提示：《Windows核心编程（第5版•英文版）》深入剖析了Windows程序员必须掌握的底层实现机理，通过大量贴近实战、精心编写的代码，详细阐述了Windows的各种基本要素，如字符和字符串、内核对象、进程、作业、线程、纤程、内存管理、DLL和异常处理等。本文介绍了微软新发布的64-Bit Windows，并和32-bit windows进行对比，对其优势和特性进行了简单描述。

64-Bit Windows

Microsoft has been shipping 32-bit versions of Windows that support the x86 CPU architecture for many years. Today, Microsoft also offers 64-bit versions of Windows that support the x64 and IA-64 CPU architectures. Machines based on these 64-bit CPU architectures are fast gaining acceptance. In fact, in the very near future, it is expected that all desktop and server machines will contain 64-bit CPUs. Because of this, Microsoft has stated that Windows Server 2008 will be the last 32-bit version of Windows ever! For developers, now is the time to focus on making sure your applications run correctly on 64-bit Windows. To this end, this book includes solid coverage of what you need to know to have your applications run on 64-bit Windows (as well as 32-bit Windows).

The biggest advantage your application gets from a 64-bit address space is the ability to easily manipulate large amounts of data, because your process is no longer constrained to a 2-GB usable address space. Even if your application doesn't need all this address space, Windows itself takes advantage of the significantly larger address space (about 8 terabytes), allowing it to run faster.

Here is a quick look at what you need to know about 64-bit Windows:

    The 64-bit Windows kernel is a port of the 32-bit Windows kernel. This means that all the details and intricacies that you've learned about 32-bit Windows still apply in the 64-bit world. In fact, Microsoft has modified the 32-bit Windows source code so that it can be compiled to produce a 32-bit or a 64-bit system. They have just one source-code base, so new features and bug fixes are simultaneously applied to both systems.

    Because the kernels use the same code and underlying concepts, the Windows API is identical on both platforms. This means that you do not have to redesign or reimplement your application to work on 64-bit Windows. You can simply make slight modifications to your source code and then rebuild.

    For backward compatibility, 64-bit Windows can execute 32-bit applications. However, your application's performance will improve if the application is built as a true 64-bit application.

    Because it is so easy to port 32-bit code, there are already device drivers, tools, and applications available for 64-bit Windows. Unfortunately, Visual Studio is a native 32-bit application and Microsoft seems to be in no hurry to port it to be a native 64-bit application. However, the good news is that 32-bit Visual Studio does run quite well on 64-bit Windows; it just has a limited address space for its own data structures. And Visual Studio does allow you to debug a 64-bit application.

    There is little new for you to learn. You'll be happy to know that most data types remain 32 bits wide. These include ints, DWORDs, LONGs, BOOLs, and so on. In fact, you mostly just need to worry about pointers and handles, since they are now 64-bit values.

Because Microsoft offers so much information on how to modify your existing source code to be 64-bit ready, I will not go into those details in this book. However, I thought about 64-bit Windows as I wrote each chapter. Where appropriate, I have included information specific to 64-bit Windows. In addition, I have compiled and tested all the sample applications in this book for 64-bit Windows. So, if you follow the sample applications in this book and do as I've done, you should have no trouble creating a single source-code base that you can easily compile for 32-bit or 64-bit Windows.

 

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