Threading and Synchronization Second Level
The second level of threading and synchronization is the same as the third level, except that video memory is not evicted to host CPU memory. In other words, the Windows Display Driver Model (WDDM) guarantees that only a single thread (that is, the calling thread) is within the display miniport driver, the graphics hardware is idle, and no direct memory access (DMA) buffers are currently being processed by the driver or passed through the GPU scheduler. The following calls into the display miniport driver are made under the second level:
Note In order for some calls to be made under the second level, the HardwareAccess flag must be set within the D3DDDI_ESCAPEFLAGS structure that is a member of DXGKARG_ESCAPE. If this flag is not set, then the call will fail.