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    SubjectRe: linear vs. logical addresses? how does cpu interpret kernel addrs?
    On Tue, 16 Sep 2003, Ben Johnson wrote:

    > short version:
    >
    > 1) When I am referencing a pointer in the kernel, is the value of that
    > pointer variable interpreted by the cpu as a logical or linear address?
    >
    > 2) if I have two overlapping data/stack segments presently selected,
    > each with a different base, how does the cpu know which segment/base
    > address to use to get the linear address?
    >
    [SNIPPED...]
    All stack offsets are accessed relative to SS. No exceptions.
    However a compiler may calculate those offsets based upon
    something else.
    This is why DS must equal SS if 'C' is going to access both
    stack data variables and data segment variables. This is how
    the 'C' code converter is set up. It is not a CPU limitation.
    If you change the SS in the kernel, strange and wonderful
    things will occur.


    Cheers,
    Dick Johnson
    Penguin : Linux version 2.4.22 on an i686 machine (794.73 BogoMips).
    Note 96.31% of all statistics are fiction.


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