Select all that applies. In addressing limitations on how to wait for output using kernel buffers, it is OK if Upper layer semaphore may wait on buffer space in Middle layer to produce output Upper...

Extracted text: Select all that applies. In addressing limitations on how to wait for output using kernel buffers, it is OK if Upper layer semaphore may wait on buffer space in Middle layer to produce output Upper layer semaphore may signal the Middle layer semaphore when it produces output Middle layer semaphore may wait on buffer space in Lower layer to produce output O Middle layer semaphore may signal the Lower layer semaphore when it produces output