CS 450 Update Log

Following is a set of problems that should help you prepare for the v6 portion of the upcoming exam:

• Describe the memory management facilities of the PDP11/40. Specifically, detail the physical/virtual address spaces, and the mapping mechanism used by the MMU.

• What is the resulting memory mapping by the end of line 0669? Does proc 0’s user structure necessarily begin at the beginning of the 6th physical page? Why or why not?

• What is the structure always to be found at virtual address 140000 in the kernel’s address space? What is the significance of this structure, and what must the kernel do with it when switching to a different process?

• What does the stack pointer point to after line 2228 in the first call to swtch, after the kernel booted?

• What data structures are associated with each process in v6? Describe the roles that they play during a process’s lifetime.

• Annotate every line of assembly code for the function _retu, from lines 0740-0749. What does each statement do, and why?

• Explain why the calls to savu and retu are found in the swtch routine at lines 2189, 2193, and 2228. You should describe the processes involved during the function’s execution.