When developing the 64-bit version of an application, you should also be very attentive to the issue of program distribution - you might encounter some peculiar problems when installing the program on a 64-bit operating system, and if you forget about them, you will get a non-working installation package.

1. Lesson 27. Peculiarities of creating
installers for a 64-bit environment
When developing the 64-bit version of an application, you should also be very attentive to the issue of
program distribution - you might encounter some peculiar problems when installing the program on a
64-bit operating system, and if you forget about them, you will get a non-working installation package.
First of all you should understand that the program installer itself (the exe-file that launches the
installation process) can technically be either a 32-bit application or a 64-bit one. If you make this
installer 64-bit, it will not work on a 32-bit system. Note that you will not see a message like: "You are
trying to install a distribution kit of a 64-bit program on a 32-bit system". It will simply generate a
message about a damaged file. Thus, it is most often reasonable to make the installer a 32-bit
application even if it will be installed only on a 64-bit system.
An important issue of operation of 32-bit programs in the 64-bit environment is the redirection
mechanism implemented in Windows. This mechanism arranges the work of obsolete 32-bit
applications so that when trying to access, for instance, the folder "c:program files", they are
automatically redirected to "c:program files (x86)". The access to some register sections is also
automatically redirected.
When developing installers, the redirection mechanism may often lead to a situation when the files
appear in some other place than the developer has expected, or the register entries relate to some
other sections than they should. You may read about the redirection system in MSDN Help system: "File
System Redirector".
All these specifics can be set in any contemporary installer but you should not forget about it while
creating a distribution kit compatible with 64-bit operating systems.
When developing installers for 64-bit versions, developers often make one common installer that
contains both the 32-bit and 64-bit versions of the applications and their components. In this case, do
not forget to add full sets of components and dependent libraries. For example, developers often add
Visual C++ Redistributable Package into the installation package for applications developed with Visual
C++. This package must be included both for the x86 and x64 versions.
If your installer uses some third-party units to implement complex functionality, you should remember
about the restriction - units built for the 64-bit mode cannot load 32-bit dynamic libraries and vice versa.
The course authors: Andrey Karpov (karpov@viva64.com), Evgeniy Ryzhkov (evg@viva64.com).
The rightholder of the course "Lessons on development of 64-bit C/C++ applications" is OOO "Program
Verification Systems". The company develops software in the sphere of source program code analysis.
The company's site: http://www.viva64.com.
Contacts: e-mail: support@viva64.com, Tula, 300027, PO box 1800.