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class filter driver vs device specific filter driver. RRS feed

  • Question

  • I have just started working with windows driver(specially KMDF based filter drivers).I have been looking out for this but did not get exactly which to use when ?
    Monday, July 15, 2013 10:05 AM

Answers

  • Typically you use a class driver when you want to modify the behavior of most if not all of the devices of a particular type.  For instance, you want to encrypt all disks on the system (except perhaps the boot disk).   You use a device specific filter when you want to deal with a specific instance of a device, i.e. only encrypt one disk. 

    There is a gray area in the middle.  For some devices it is easier to do a class filter, then in the AddDevice routine (or perhaps start device handling) determine if the particlar device below you is something you want to filter.  For these you need a conditional so that if the device is not to be filtered you just pass all requests through quickly.


    Don Burn Windows Filesystem and Driver Consulting Website: http://www.windrvr.com Blog: http://msmvps.com/blogs/WinDrvr

    Monday, July 15, 2013 10:29 AM