A system has a 3 ring security model . Ring 0 is used for a hypervisor, HV, managing virtual machines, Ring 1 is used for the O/S kernel of any of the virtual machines running, and Ring 2 is used by applications running in those virtual machines. 

Assume we have AppA running on Linux in VmA and AppB running on BSD on VmB on the above system. AppB and AppA have opened a network socket between them and have can use system calls to read from and write from the socket, readSock() and writeSock(). 

a) AppA perfoms a writeSock() system call. What happens in terms of the system call interface and the ring values?

b) What must happen for the data to be transferred between VMs? (in terms of rings)

c) Assume AppB is waiting for data having called readSock(). What does the BSD kernel have to do to get the data to AppB.