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    SubjectRe: Pentium bug fix
    > I'm already running 2.0.32 which fixes the f00f bug.  However, I'm very
    > curious as to exactly how the invalid opcode was trapped. I have the
    > source code, but can we just have some description on how the fix works?
    > I'd really like to know.

    Please search the linux-kernel archives, you'll find a lot of
    discussion about this question.

    In short, the best known fix masks the interrupt descriptor table as
    read-only. When the processor executes this invalid instruction, it
    apparently requires write permissions for the IDT, which in turn
    leads to a page fault. The protection fault handler checks whether
    it accessed the IDT, then produces SIGILL, otherwise SIGSEGV.

    Older versions of the patch completely unmapped this part of the
    IDT, causing a page fault for every of the first six faults.


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