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    SubjectRe: RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64 with MCP51 laptops
    > Most, probably most-all, of the delays to port operations
    > on modern ix86 machines are not needed at all. Certainly

    We know this. The problem is that there is no good known way to
    figure out which machines need it. Also it is typically
    slow hardware anyways -- the most time critical is probably
    the 8259, but nobody who cares about performance still uses
    it except as a fail safe fallback and for those it is better
    to be conservative.

    > machines that use bridges to expand port I/O to the ISA
    > bus do need any such delays. There are exactly two (and

    It has been observed to be required talking to some older
    PCI based northbridges too.

    > (2) I/O operations that have two ports, one an index
    > port and the other a data port, like the CMOS RTC. Once

    and PIT etc.

    Anyways it looks like the discussion here is going in a
    a loop. I had hoped David would post his test results with
    another port so that we know for sure that the bus aborts
    (and not port 80) is the problem on his box. But it looks like
    he doesn't want to do this. Still removing the bus aborts
    is probably the correct way to go forward.

    Only needs a patch now. If nobody beats me to it i'll
    add one later to my tree.


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      Last update: 2007-12-11 17:33    [W:0.047 / U:3.876 seconds]
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