Messages in this thread | | | Date | Sun, 23 Nov 2003 22:03:57 -0800 | From | William Lee Irwin III <> | Subject | Re: PTE --> 2 values?? |
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On Sun, Nov 23, 2003 at 11:50:15PM -0500, John Smith wrote: > I saw that Linux is using a 3 level page tables, pgd, pmd and pte. The value > in the pte can refer to an actual page in memory OR an address on the swap > device. How does the kernel distinguish the two values such that if the > value is refering to an swap device address, it will not lookup the address > in memory ??
There is a present bit. All other bits are available to the OS when the present bit says "not present". On many machines, Linux' 3-level tree is a pure software construct, and the processor is informed of translations in other ways (e.g. inverted pagetables, direct TLB insertion).
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