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"UpperFilters" of what ? RRS feed

  • Question

  • Hi Experts:

    I'm trying to understand the meaning of "UpperFilters" in the INF file. I saw a sample line below.

    Can someone please explain to me what is the term "UpperFilters" relate to? I think the lines below

    says "cdaudio" is a "UpperFilters", but I'm wondering it's upperFilter of WHAT ?

    Thanks in advance

    [changer_install.HW] AddReg=changer_addreg [cdaudio_addreg] ; changer_addreg section has similar entry HKR,,"UpperFilters",0x00010000,"cdaudio" ; REG_MULTI_SZ value


    leo

    Thursday, August 30, 2018 9:29 PM

Answers

  • Even though no one writes WDM drivers anymore, the docs and terminology are still relevant: Types of WDM Drivers. In your case, the function driver is CDAUDIO, and the Changer is an upper filter that logically sits on top of CDAUDIO, which means that the Changer driver sees all I/O requests coming into the DevStack before CDAUDIO, and after CDAUDIO completes a request.

     -Brian


    Azius Developer Training www.azius.com Windows device driver, internals, security, & forensics training and consulting. Blog at www.azius.com/blog

    Thursday, August 30, 2018 9:58 PM
    Moderator