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    SubjectRe: Adding kmap_atomic_prot_pfn

    * Thomas Hellström <thomas@tungstengraphics.com> wrote:

    > Ingo Molnar wrote:
    >> * Thomas Hellström <thomas@tungstengraphics.com> wrote:
    >>
    >>
    >>> Keith,
    >>>
    >>> What you actually are doing here is claiming copyright on code that
    >>> other people have written, and tighten the export restrictions.
    >>> kmap_atomic_prot_pfn() appeared long ago in drm git with identical
    >>> code and purpose, but with different authors, and iounmap_atomic is
    >>> identical to kunmap_atomic.
    >>>
    >>
    >>
    >>>> +EXPORT_SYMBOL_GPL(iomap_atomic_prot_pfn);
    >>>>
    >>
    >> you want to use this facility in a binary-only driver?
    >>
    >> Ingo
    >>
    > At this point I have no such use for it, no.
    > The original user was a MIT style licenced driver.

    okay, then just to put this question to rest: i wrote the original
    32-bit highmem code ~10 years ago. I wrote the first version of fixmap
    support - in fact i coined the term. I wrote the first version of the
    atomic-kmap facility as well.

    All of that code is licensed under the GPLv2. So if anyone wants to make
    any copyright claims about highmem/kmap/fixmap derivative works,
    consider it in that light.

    Regarding this new API variant that Keith wrote: it would be silly and
    dangerous to export it anywhere but to in-kernel drivers. The API
    disables preemption on 32-bit and rummages deep in the guts of the
    kernel as well, uses up a precious resource (fixmap slots), etc. It's
    internal and we eventually might want to deprecate forms of it and
    concentrate on the good 64-bit performance side.

    Ingo
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