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Sept/Oct 2019 Issue of The NT Insider available


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Minifilter instance in different frames

parsaparsa Member Posts: 5

Hello All, I am learning minifilter driver development. I have a question on my mind and i found this great forum to get help. Here is my question.

Whether a minifilter can be attached to different frames. I believe we can. But my doubt is , for example, as shown in this link https://docs.microsoft.com/en-us/windows-hardware/drivers/ifs/filter-manager-concepts, is it OK to attach MiniFilter B on top of MiniFilter D in Frame 0?
I believe that the altitude range in one frame (frame 0) does not care about altitude range in another frame (frame 1) on top or below it.

Thanks,
Jay

Comments

  • rod_widdowsonrod_widdowson Member - All Emails Posts: 1,073

    If you are still learning I wouldn't worry about frames. They should be on their way out as old style fsfilters get ported.

    Having used multiple instances in a driver I don't see any reason why they shouldn't work as you expect whether there is a frame change in the way or not, but I have no experience to back up this assertion.

  • parsaparsa Member Posts: 5

    Thanks for your reply. This leads me one more question. If i have multiple instance on the same frame or different frame, how the lock mechanism works. If one instance acquired the lock and reaching the another instance through different frames, then lock acquiring code in the second instance will not succeed. Is my understanding wrong?

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