class DriverReservesRingBufferSpace

Clients request minimum VMO sizes for their requirements, and drivers must respond with VMOs that

satisfy those requests as well as their own constraints for proper operation. A driver or device

reads/writes a ring buffer in batches, so it must reserve part of the ring buffer for safe

copying. This test case validates that drivers set aside a non-zero amount of their ring buffers.

Many drivers automatically "round up" their VMO to a memory page boundary, regardless of space

needed for proper DMA. To factor this out, here the client requests enough frames to exactly fill

an integral number of memory pages. The driver should nonetheless return a larger buffer.