remzi-arpacidusseau / ostep-typos

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Chapter 20: Wrong or Confusing Figure 20.1 #105

Open madball92 opened 2 months ago

madball92 commented 2 months ago

Firstly, I'd like to thank you for this great work. It's really interesting and attractive. Thank you, Sir!

The problem I found is that: According to previous chapter (Figure 18.2 or Figure 18.4), the number of frames should equal to the number of pages, as well as the number of page table entries. In this way, all physical memory frames are or will be 1-1 mapped to virtual pages. But in Figure 20.1, the frame numbers (32) are bigger than page numbers (16). In this way, even if all virtual pages are mapped to physical memory, there are still 16 unused frames, which could be wrong.

If I'm right about the problem, Figure 20.2 and introduction of the example should be changed accordingly.

My name is Kai Liu.

PS. For anybody seeing this issue, if you find I'm wrong and can help me correcting my thought, PLEASE REPLY. Thank you!