Implementation

Assume that we want to create an OS using a multiserver approach, similar to how it is done in MINIX 3 (j.mp/minix3) or GNU Hurd (j.mp/gnuhurd). A multiserver OS has a minimal kernel, called the microkernel, which runs in privileged mode. All the other services of the system are following a server architecture (driver server, process server, file server, and so forth). Each server belongs to a different memory address space and runs on top of the microkernel in user mode. The pros of this approach are that the OS can become more fault-tolerant, reliable, and secure. For example, since all drivers are running in user mode on a driver server, a bug in a driver cannot crash the whole system, nor can it affect the other servers. The cons of this approach are the performance overhead and the complexity of system programming. These are a result of the communication happening between a server and the microkernel, as well as between the independent servers, using message passing...