Microsoft KB Archive/170426

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PRB: VirtualProtect Limitations on Windows 95

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Q170426

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The information in this article applies to:


 * Microsoft Win32 Application Programming Interface (API), included with:
 * Microsoft Windows 95

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SYMPTOMS
VirtualProtect and VirtualProtectEx functions fail with ERROR_INVALID_PARAMETER when you are setting access protection for a region of pages committed to a memory-mapped file.

CAUSE
VirtualProtect and VirtualProtectEx are not supported for memory that is mapped to the shared memory region (addresses between 2 GB and 3 GB), and the system memory regions (addresses between 3 GB and 4 GB). Since all memory-mapped files in Windows 95 are mapped to this region, the VirtualProtect functions are not supported for them.

STATUS
This behavior is by design.

MORE INFORMATION
NOTE: The VirtualProtect and VirtualProtectEx functions may succeed under certain circumstances when attempting to set access protection to PAGE_READONLY or PAGE_NOACCESS for pages in the shared memory regions. This behavior should not be relied upon, and can cause other undesirable behavior.

Additional query words: VirtualProtect VirtualProtectEx Win95

Keywords : kbAPI kbKernBase kbGrpDSKernBase

Issue type : kbprb

Technology : kbAudDeveloper kbWin32sSearch kbWin32API