# CMAKE_GENERATOR_PLATFORM

New in version 3.1.

Generator-specific target platform specification provided by user.

Some CMake generators support a target platform name to be given to the native build system to choose a compiler toolchain. If the user specifies a platform name (e.g. via the `cmake -A` option or via the `CMAKE_GENERATOR_PLATFORM` environment variable) the value will be available in this variable.

The value of this variable should never be modified by project code. A toolchain file specified by the `CMAKE_TOOLCHAIN_FILE` variable may initialize `CMAKE_GENERATOR_PLATFORM`. Once a given build tree has been initialized with a particular value for this variable, changing the value has undefined behavior.

Platform specification is supported only on specific generators:

- For Visual Studio Generators with VS 2005 and above this specifies the target architecture.

- For `Green Hills MULTI` this specifies the target architecture.

See native build system documentation for allowed platform names.

## Visual Studio Platform Selection

The Visual Studio Generators support platform specification using one of these forms:

- `platform`

- `platform[,key=value]*`

- `key=value[,key=value]*`

The `platform` specifies the target platform (VS target architecture), such as `x64`, `ARM64`, or `Win32`. The selected platform name is provided in the `CMAKE_VS_PLATFORM_NAME` variable.

The `key=value` pairs form a comma-separated list of options to specify generator-specific details of the platform selection. Supported pairs are:

`version=<version>`

  New in version 3.27.

  Specify the Windows SDK version to use. This is supported by VS 2015 and above when targeting Windows or Windows Store. CMake will set the `CMAKE_VS_WINDOWS_TARGET_PLATFORM_VERSION` variable to the selected SDK version.

  The `<version>` may be one of:

  `10.0`

    Specify that any 10.0 SDK version may be used, and let Visual Studio pick one. This is supported by VS 2019 and above.

  `10.0.<build>.<increment>`

    Specify the exact 4-component SDK version, e.g., `10.0.19041.0`. The specified version of the SDK must be installed. It may not exceed the value of `CMAKE_VS_WINDOWS_TARGET_PLATFORM_VERSION_MAXIMUM`, if that variable is set.

  `8.1`

    Specify the 8.1 SDK version. This is always supported by VS 2015. On VS 2017 and above the 8.1 SDK must be installed.

  If the `version` field is not specified, CMake selects a version as described in the `CMAKE_VS_WINDOWS_TARGET_PLATFORM_VERSION` variable documentation.