Microsoft KB Archive/229035

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INFO: Kernel Mode Drivers Are Read-Only in Windows 2000

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Q229035

This article discusses a Beta release of a Microsoft product. The information in this article is provided as-is and is subject to change without notice.

No formal product support is available from Microsoft for this Beta product. For information about obtaining support for a Beta release, please see the documentation included with the Beta product files, or check the Web location from which you downloaded the release.

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The information in this article applies to:


 * Microsoft Windows 2000 Driver Development Kit (DDK)

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SUMMARY
In Windows 2000, kernel mode device drivers cannot write to read-only segments of memory.

MORE INFORMATION
In previous versions of Windows, kernel mode device drivers can modify their own segments of memory while loaded; however, Windows 2000 enforces read-only access to pages in memory that are not specifically marked as writable.

The Windows 2000 Memory Manager does not allow kernel mode device drivers to modify their own system code at run time, or to modify a string constant that has been previously initialized. To declare a global string that can be modified, the string should be declared as an array of L-value characters.

If a kernel-mode driver or application attempts to write to a read-only memory segment, the system issues bug check 0xBE and a blue screen is displayed with error information.