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    SubjectRe: [RFC] Splitting kernel headers and deprecating __KERNEL__
    Linus Torvalds wrote:
    > Ok, this discussion has gone on for too long anyway, but let's make it
    > easier for everybody. The kernel uses u8/u16/u32 because:
    > - the kernel should not depend on, or pollute user-space naming.
    > YOU MUST NOT USE "uint32_t" when that may not be defined, and
    > user-space rules for when it is defined are arcane and totally
    > arbitrary.

    Hmm, so you're predicting problems if user space includes something
    that uses uint32_t ? Wouldn't either of these work (descriptive file
    names for clarity):

    1) include/linux-user/foo.h:
    #include <stdint.h>
    #include <linux-kernel-and-user-common/foo.h>

    #include <linux/stdint.h>
    #include <linux-kernel-and-user-common/foo.h>

    (And document that anything under linux-user may pull in a
    certain set of standard headers, such as stdint.h, maybe
    sys/types.h, etc.)

    2) include/linux-user/foo.h:
    #ifndef __KERNEL__
    #include <stdint.h>
    #include <linux/stdint.h> /* if we want this */
    foo stuff (or some include)

    Idem. (Sort of the opposite of what we have today.)

    3) just require that some stdint.h has been included before
    including linux-user/foo.h

    For user space that absolutely insists on doing its own uint32_t,
    a refined variant of case 3 (i.e. detailing of what exactly is
    expected to be defined) or, in case 1, direct use of
    linux-kernel-and-user-common/foo.h along with the definition from
    case 3 should work.

    There are other cases where a header file may pull in other
    definitions, e.g. for fcntl.h, POSIX decrees

    | Inclusion of the <fcntl.h> header may also make visible all
    | symbols from <sys/stat.h> and <unistd.h>.

    So the semantics of for cases 1 and 2 would be consistent with
    current POSIX practice.

    What am I missing ?

    - Werner

    / Werner Almesberger, Buenos Aires, Argentina /
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