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Why do all I/O is buffered in UMDF? RRS feed

  • Question

  • 1. Why do all I/O transfer is buffered in case UMDF?

    2. Why do need to specify the I/O transfer type that each device object support in case of KMDF?

    3. What will happen if not specify the I/O transfer type in case of KMDF?

    Saturday, May 4, 2013 11:55 AM

Answers

  • 1 because initially that was the simplest thing to do. Direct Io is complicated for umdf, we don't want to map partial pages or expose app or kernel data. Since win8 you can enable direct

    2 this is not kmdf specific. Wdk requires this. You must specify how to copy or map memory at the device level for read and write, each ioctl can have its own encoding

    3 buffers io

    22 io


    d -- This posting is provided "AS IS" with no warranties, and confers no rights.

    Saturday, May 4, 2013 2:43 PM