This function is declared in the coresrv/io/dma.h file.
Retcode KnIoDmaBegin(Handle rid, Handle *handle);
Allows the device to access the DMA buffer with the handle rid.
Output parameter handle contains the handle of this permission.
If successful, the function returns rcOk.
For a usage example, see KnIoDmaCreate().
To prevent a device from accessing the DMA buffer, you need to call the KnIoClose() function while passing the specified handle of the permission in this function.