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    SubjectRe: How does the kernel map physical to virtual addresses?
    Hi,

    On Mon, Aug 28, 2000 at 01:56:34PM +0100, Tigran Aivazian wrote:
    >
    > it is interesting to observe that many questions that deal with _details_
    > are answered quickly but questions related to fundamental concepts related
    > to how Linux is designed, baffle all of us (since 0 people answered). So,
    > is there really nobody in the whole world who can answer this? I would
    > like to know the answer (about global kernel memory layout - i.e. what
    > goes into PSE pages and what goes into normal ones, and how does PAE mode
    > change the picture?) myself...

    If PSE is available, it is used to map the bits of the kernel's
    VA which permanently maps all of physical memory. As a result, those
    pages cannot necessarily be looked up via a normal page table walk.
    Anything dynamically mapped --- ie. high pages (if using PAE), or
    vmalloc/ioremap pages --- is mapped using normal 4k ptes.

    mem_map[] is completely unaffected by the use of PSE, and continues to
    keep one entry per 4k physical page regardless of how the page tables
    have been constructed.

    --Stephen
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