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    SubjectRe: can somebody explain barrier() macro ?
    On Tue, Feb 20, 2001 at 12:50:54PM -0700, wrote:
    > barrier() is defined in kernel.h as follows :
    > #define barrier() __asm__ __volatile__("": : :"memory")
    > what does this mean ? is this like "nop" ?

    It's a write barrier. It prevents the compiler from optimising writes
    to memory: all outstanding writes should be done before the program
    flow crosses the barrier().


    J.A.K. (Erik) Mouw, Information and Communication Theory Group, Department
    of Electrical Engineering, Faculty of Information Technology and Systems,
    Delft University of Technology, PO BOX 5031, 2600 GA Delft, The Netherlands
    Phone: +31-15-2783635 Fax: +31-15-2781843 Email:
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