NX Pool Opt-In Mechanisms

To port kernel-mode driver code to Windows 8 from earlier versions of Windows, you should use the NonPagedPoolNx type of memory pool as a best practice. You can use one of several porting aids to easily "opt in" to use the NonPagedPoolNx pool type by default.

These porting aids use one or both of the following techniques to enable the driver to use NX nonpaged pool:

• Use a #define preprocessor statement to create a globally defined macro name.

• Call an inline function from the DriverEntry routine.

For most kernel-mode driver code, these porting aids enable developers to update their drivers with minimal effort.

In this section

Topic	Description
Single Binary Opt-In: POOL_NX_OPTIN	To build a single driver binary that runs both in Windows 8 and in earlier versions of Windows, use the POOL_NX_OPTIN opt-in mechanism. This is a porting aid for third-party hardware vendors who supply a single driver binary to support multiple Windows versions.
Multiple Binary Opt-In: POOL_NX_OPTIN_AUTO	If you are a hardware vendor who supplies different driver binaries for different versions of Windows, you can use the POOL_NX_OPTIN_AUTO opt-in mechanism. This porting aid builds a separate driver binary for Windows 8 and for each earlier version of Windows that your driver supports.
Selective Opt-Out: POOL_NX_OPTOUT	You can globally enable one of the no-execute (NX) pool opt-in mechanisms for a set of driver source files, and then override this opt-in mechanism for one or more selected source files with POOL_NX_OPTOUT. This allows the selected source files to continue to use executable nonpaged memory. You can use the POOL_NX_OPTOUT opt-out mechanism with either the POOL_NX_OPTIN or the POOL_NX_OPTIN_AUTO opt-in mechanism.