Messages in this thread | | | Date | Fri, 24 Oct 2008 11:32:33 +0200 | From | Ingo Molnar <> | Subject | Re: Adding kmap_atomic_prot_pfn |
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* 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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