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    SubjectRe: Linux-2.4.0-test9-pre2


    On Mon, 18 Sep 2000, Chris Wedgwood wrote:

    > On Sun, Sep 17, 2000 at 10:37:51AM -0700, Linus Torvalds wrote:
    >
    > - "extern inline" -> "static inline". It doesn't matter right now,
    > but it's proactive for future gcc versions.
    >
    > can someone please explain the difference?

    Let's assume that gcc decides that it won't inline a function, because
    it's too "big", according to some gcc definition of "big".

    With "extern inline", the function will not exist AT ALL, and you'll end
    up getting a link-time error complaining about the lack of that function.

    With "static inline", gcc will emit the function as a separate function
    for that compilation block if it didn't get inlined.

    Both are valid things. You use "extern inline" when you have a "backing
    store" for the funcion (ie you do have the non-inlined version in a
    library somewhere). You use "static inline" when you don't.

    For the kernel, we very seldom have the non-inlined versions in any
    library, so for the kernel "extern inline" is almost always the wrong
    thing.

    Note that with most versions of gcc this is all a complete non-issue, as
    most versions of gcc will _always_ inline a function that the user has
    asked to be inlined. So the issue seldom actually comes up.

    Linus

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