| Photography: Power In A Single Frame - Canon “Path To Mastery” Series With Tyler Stableford | Canon EOS Webcam Utility for Mac – Use your DSLR as a Webcam or Streaming Camera | Canon EOS Webcam for Windows – Use your DSLR as a Webcam or Streaming Camera | Canon Tech Tip: Face Detection Autofocus | Canon EOS Webcam Utility: How to Stand Out in Your Video Meetings | Canon Camera Connect App with Mike | Cinematography: The Art Of Powerful Storytelling - “Path To Mastery” Series With Tyler Stableford | Canon Tech Tip: How to build a custom look in our Cinema EOS cameras. | Canon Tech Tip: Controlling your Cinema EOS camera from a compatible Wifi device | Canon Tech Tip: Log Curves in Cinema EOS Camera | Canon Tech Tip: Cinema Raw Development | Canon Tech Tip: Audio backup in Cinema EOS Cameras | Canon Tech Tip: Canon Tilt Shift Lenses | Canon’s XF705 Professional Camcorder H.265 Update | XF705 Firmware Update (May 2020) | Generally, mass-storage device drivers request direct I/O for transfer requests, including lowest-level drivers that use direct memory access (DMA) or programmed I/O (PIO), as well as any intermediate drivers chained above them. Download Direct Color Port Devices Drivers The I/O manager determines that an I/O operation is using direct I/O as follows: For IRP_MJ_READ and IRP_MJ_WRITE requests, DO_DIRECT_IO is set in the Flags member of the DEVICE_OBJECT structure. For more information, see Initializing a Device Object. For IRP_MJ_DEVICE_CONTROL and IRP_MJ_INTERNAL_DEVICE_CONTROL requests, the IOCTL code's value contains METHOD_IN_DIRECT or METHOD_OUT_DIRECT as the TransferType value in the IOCTL value. For more information, see Defining I/O Control Codes.
Drivers that use direct I/O will sometimes also use buffered I/O to handle some IRPs. In particular, drivers typically use buffered I/O for some I/O control codes for IRP_MJ_DEVICE_CONTROL requests that require data transfers, regardless of whether the driver uses direct I/O for read and write operations. Setting up a direct I/O transfer varies slightly, depending on whether DMA or PIO is being used. For more information, see: Download Direct Color Port Devices Driver EdDrivers must take steps to maintain cache coherency during DMA and PIO transfers. For more information, see Maintaining Cache Coherency.
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