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    SubjectRe: [RFC patch 08/18] cnt32_to_63 should use smp_rmb()

    On Fri, 7 Nov 2008, Mathieu Desnoyers wrote:
    > I want to make sure
    > __m_cnt_hi
    > is read before
    > mmio cnt_lo read

    Hmm, let me make sure I understand why there is no wmb.

    Paul, can you verify this?

    Mathieu, you do the following:

    read a
    reab b
    if (test b)
    write a

    So the idea is that you must read b to test it. And since we must read a
    before reading b we can see that we write a before either?

    The question remains, can the write happen before either of the reads?

    But since the read b is reading the hw clock, perhaps that just implies a
    wmb on the hardware side?

    -- Steve

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      Last update: 2008-11-07 21:11    [W:0.025 / U:4.260 seconds]
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