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    SubjectRe: [RFC][PATCH 0/2] KABI example conversion and cleanup
    On Mar 26, 2006, at 18:06:48, Eric Piel wrote:
    > The real problem of sharing the same headers between kernel and
    > KABI is that it will end up by having to re-implement the "#ifdef
    > __KERNEL__"'s. Have a look at Kyle's second patch "Generalize
    > fd_set handling across architectures". Some headers had a different
    > version of the __FD_*() macros depending on the compiler. That's
    > something you may want to have in the implementation but definitely
    > not in the specification.

    Actually, I think it's the other way around. The <kabi/*.h> files
    should (eventually) be useable in basically any compilation
    environment thrown at it. This means it should work from C and C++,
    using GCC, ICC, or some custom barely-standards-compliant compiler.
    I didn't bother with that part right now, since I still want to try
    to reuse the generic bitops if possible, but it's something I plan to
    address in future versions of the patchset (see below).

    > In this situation, Kyle handled it nicely by writing versions
    > compatible with any compiler.

    Eh, not really. "__inline__" is GCC-specific and probably won't work
    in other compilers (unless you did "#define __inline__", which would
    bloat the code a lot).

    This case highlights something else I'd like to do. A good chunk of
    the functionality in the Linux kernel works both in userspace and
    kernelspace, and some of those arch-specific primitives (like the
    inline bitops) would be useful in defining the kabi headers.
    According to Jeff Dike, UML would like access to some of that stuff
    unrestricted by __KERNEL__ too. In all of those cases, it's not an
    ABI and all the users are in-kernel so it could be changed at will.
    I'd like to try to put some of that into a "klib" directory (though
    with dependencies crossing between kabi and klib) so that it could be
    used in kabi and UML without duplicating functionality. Naturally
    much of that would be C-only and depend on GCC, but I would have to
    be careful that the kabi portions used least-common-denominator

    That brings up one final point: Does anybody actually use any
    compilers on Linux other than GCC?

    Kyle Moffett

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