GetWriteWatch doesn' work for x64 applications

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I'm trying to detect when application writes to the memory. For that reason I'm using VirtualAlloc with MEM_COMMIT | MEM_RESERVE | MEM_WRITE_WATCH flags, ResetWriteWatch and GetWriteWatch. For x86 applications this works excellent. But I have problem with x64 apps: While VirtualAlloc and ResetWriteWatch are successfully executed, GetWriteWatch returns error. GetLastError returns "Invalid access to memory location" code. Does anyone know why it happens?

I installed hooks on DX9. So on Idirect3DIndexBuffer::Lock and IDirect3DVertexBuffer::Lock I allocate new buffer by VirtualAlloc with MEM_COMMIT | MEM_RESERVE | MEM_WRITE_WATCH flags, reset memory by ResetWriteWatch. And outout it instead the one which is returned by Lock. On Unlock (before it actually happens) I want to get the array of pages where write was performed by GetWriteWatch. Result: ok for x86 application and fail for x64. I wonder if there any limitations for using that API on x64 platform?
So to summarize: X64 paltform -> on x86 application GetWriteWatch succeeded, on x64 failed.

Posted 15-Sep-11 20:35pm

Eldethar88

Updated 18-Sep-11 21:13pm

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Mehdi Gholam · Answer 1 · 2011-09-16T20:16:00

Solution 1

From MSDN : "64-bit Windows on Itanium-based systems: Due to the difference in page sizes, GetWriteWatch is not supported for 32-bit applications."

Take a look at the following link also : here

Posted 16-Sep-11 20:16pm

Mehdi Gholam

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Eldethar88 19-Sep-11 2:59am

Thank you for you answer, Mendi. I saw this info on MSDN. The problem is that I run x64 application on x64 platform. I don't see any obvious reasons for GetWriteWatch to fail.