64-bit Install Mode

An installation can run in one of two modes: 32-bit or 64-bit. By default, 32-bit install mode is used. To enable 64-bit install mode, there are two options:

• Set SetupArchitecture to x64 (recommended). This builds a 64-bit (x64) installer, and additionally enables 64-bit install mode (by default).
• Alternatively, ArchitecturesInstallIn64BitMode may be set to enable 64-bit install mode in a 32-bit installer.

It is also possible to use 32-bit install mode in a 64-bit installer — see 64-bit Inno Setup.

How do the two modes of installation differ? Primarily, the differences lie in where things are installed by default.

32-bit install mode

• Entries are 32-bit by default — refer to Entry Bitness for details.
• The {commonpf} constant is equivalent to {commonpf32}.
• The {commoncf} constant is equivalent to {commoncf32}.
• The {reg:...} constant reads the 32-bit view by default.
• The Reg* [Code] support functions access the 32-bit view by default.
• The Uninstall key is created in the 32-bit view of the registry.

64-bit install mode

• Entries are 64-bit by default — refer to Entry Bitness for details.
• The {commonpf} constant is equivalent to {commonpf64}.
• The {commoncf} constant is equivalent to {commoncf64}.
• The {reg:...} constant reads the 64-bit view by default.
• The Reg* [Code] support functions access the 64-bit view by default.
• The Uninstall key is created in the 64-bit view of the registry.