2. (a) Describe how paging works. [5 marks] (b) Can you use a buffer in userspace as a target for memory transfers using DMA from peripheral devices? Justify your answer. [5 marks] (c) A debugger makes it possible to observe and control the execution of some process and change its memory and registers. How would you use paging and/or segmentation to support a debugger? [5 marks] (d) A laboratory is used for teaching first-year programming as well as running CPU-intensive processes for research in the background. Before upgrading the memory-intensive IDE which is used for programming, the CPU was normally in use for nearly 100% of the time, and the response time was short. After the upgrade the response time has increased dramatically, and throughput has been drastically reduced. Give a possible cause for this behaviour and suggest a remedy which does not involve additional hardware. [5 marks]