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Unformatted text preview: ull) PTE 5 (null) PTE 6 (null) PTE 7 (null) PTE 8 (1K - 9) null PTEs 1023 null PTEs PTE 1023 1023 unallocated pages VP 9215 PTE 0 ... PTE 1023 gap PTE 0 ... PTE 1023 ... VP 1023 VP 1024 ... VP 2047 2K allocated VM pages for code and data 6K unallocated VM pages 1023 unallocated pages 1 allocated VM page for the stack Figure 10.18: A two-level page table hierarchy. Notice that addresses increase from top to bottom. Each PTE in the level-1 table is responsible for mapping a four-MB chunk of the virtual address space, where each chunk consists of 1024 contiguous pages. For example, PTE 0 maps the ﬁrst chunk, PTE 1 the next chunk, and so on. Given that the address space is four GB, 1024 PTEs are sufﬁcient to cover the entire space. If every page in chunk is unallocated, then level-1 PTE is null. For example, in Figure 10.18, chunks 2–7 are unallocated. However, if at least one page in chunk is allocated, then level-1 PTE points to the base of a level-2 page table. For example, in Figure 10...
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- Spring '10
- The American