cs162_fa08_mt1-14 - Problem 5b[5pts]: Assume that we wish...

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CS 162 Fall 2008 Midterm Exam I October 15, 2008 Page 17/21 Problem 5: Address Translation [18 pts] Problem 5a[3pts]: Suppose we have a 32-bit processor (with 32-bit virtual addresses) and 8 KB pages. Assume that it can address up to 2 TB (terabytes) of DRAM; 1TB = 1024 GB = (1024) 2 MB. Assume that we need 4 permissions bits in each page table entry (PTE), namely Valid (V), Writable (W), Accessed (A), and Dirty (D). Show the format of a PTE, assuming that each page should be able to hold an integer number of PTEs. If you have extra bits in the PTE, you can mark them as “unused”. Explain.
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Unformatted text preview: Problem 5b[5pts]: Assume that we wish to build a two-level page table for the processor from (5a) in which each piece of the page table consumes exactly a page (no more, no less). We may end up wasting space as a result. Draw and label a figure showing how a virtual address gets mapped into a physical address. Show the format of the page table (complete with access checks), the virtual address, and physical address. Minimize pieces of the page table that consume less than a page (and thus waste space). ....
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