Write combining and non-temporal instructions

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Write combining and non-temporal instructions

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Here is my questions:

I have a region of memory in Write Combining mode. I write to this region using a MOVNTxxx instruction. Then I use a MFENCE.

Can I say anything about the modified data reaching the main memory? In other words, is it possible to have the new data in one of the cache levels and not in the main memory?

Thanks.

P.S. Please note that I am not particularly concerned about other CPUs seeing the new data. I want to know if any statement can be made with respect to presence of the new data in main memory (DRAM).

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