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Read and write callbacks do not get invoked when registered as lower disk filter? RRS feed

  • Question

  • I am writing disk filter driver. When I install my driver as upper filter then all works fine but when I install same driver as lower filter driver by updating registry as "LowerFilters" in Disk class then my adddevice routine get invoked for all disks but read and write are not getting called. Why is it happening?
    Tuesday, March 4, 2014 9:01 AM

Answers

  • DISK.SYS is responsible for converting all operations to SCSI commands.  So any actual I/O will be seen as IRP_MJ_SCSI (which is also IRP_MJ_INTERNAL_DEVICE_CONTROL).   You will see some PnP, Power, and IOCTL requests also, but that is about it.


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

    Tuesday, March 4, 2014 12:18 PM