They set the <structfield>type</structfield> field to the respective
stream or buffer type, the <structfield>count</structfield> field to
the desired number of buffers, <structfield>memory</structfield>
-must be set to the requested I/O method and the reserved array
+must be set to the requested I/O method and the <structfield>reserved</structfield> array
must be zeroed. When the ioctl
is called with a pointer to this structure the driver will attempt to allocate
the requested number of buffers and it stores the actual number