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    SubjectRe: [PATCH] include/asm-generic/io.h: add 'UML' case just like 'no-MMU'
    On 06/26/2013 06:17 PM, Richard Weinberger wrote:
    > Am 26.06.2013 12:01, schrieb Chen Gang:
    >> > On 06/26/2013 05:48 PM, Geert Uytterhoeven wrote:
    >>> >> On Wed, Jun 26, 2013 at 11:38 AM, Richard Weinberger <richard@nod.at> wrote:
    >>>>>>> >>>>>> Since the API itself already contents the meaning: "return NULL means
    >>>>>>> >>>>>> the arch has no related io memory",
    >>> >> No, NULL means it could not map the I/O memory.
    >>> >>
    >> >
    >> > "it could not map the I/O memory" includes "has no related io memory".
    >> > So it is enough for our case.
    >> >
    >>>>>>> >>>>>> Why not define a generic dummy one in "include/asm-generic/io.h" instead
    >>>>>>> >>>>>> of "HAS_IOMEM" (which has already spread many various places, and also,
    >>>>>>> >>>>>> most of new drivers have to know about it).
    >>>>>>> >>>>>>
    >>>>>>> >>>>>> e.g: in "include/asm-generic/io.h", if "CONFIG_HAS_IOMEM=n", define a
    >>>>>>> >>>>>> dummy ioremap() which return NULL ... (also need consider more details).
    >>>>> >>>>
    >>>>> >>>> Because we don't even want to build these drivers and not make them fail while
    >>>>> >>>> executing io memory related functions.
    >>> >> Indeed, it doesn't make sense to build drivers that cannot work.
    >>> >> And they may fail in a very bad way.
    >> >
    >> > That is our 'platform' guys feeling, not the 'module' guys, as
    >> > 'platform' guys, it is better to provide the choice to 'module' guys,
    >> > and let them decide by themselves, not forced by us.
    > FYI, this is my last reply to this thread.
    >
    > As Geert and I said, drivers which need io memory have to depend on HAS_IOMEM=y.
    > If an arch does not have io memory these drivers cannot work and therefore we don't
    > want them built.

    It is really the time for stopping discussion, and thank you all for
    spending your time resources on this discussion.

    Next, I will send related patch for it (also cc to you all).


    Thanks.
    --
    Chen Gang

    Asianux Corporation


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