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    SubjectRe: bisected boot regression post 2.6.25-rc3.. please revert

    * Segher Boessenkool <segher@kernel.crashing.org> wrote:

    > so (on 32-bit) ~_PAGE_PSE is ~0x80L is 0xffffff7f, which when cast to
    > 64-bit is 0x00000000ffffff7f, so in
    >
    > (~PAGE_MASK & ~_PAGE_USER & ~_PAGE_PSE & ~_PAGE_NX)
    >
    > all the high bits are lost, while the original
    >
    > ~(PAGE_MASK | _PAGE_USER | _PAGE_PSE | _PAGE_NX)
    >
    > works as intended, since the bit inversion is done on a 64-bit number.

    but we really are interested in the low bits here (lets ignore the NX
    bit for now) and the patch has been in the queue for a long time (more
    than a month), so if there was a trivial mask mixup problem it would
    have shown on the first day. So i suspect some gcc bug instead - and
    certainly the colorful mixture of types and signs in this expression
    might have surprised a new version of gcc somewhere.

    Ingo


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