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    SubjectRe: [RFC] [PATCH] v4l2: use unsigned rather than enums in ioctl() structs
    On Thu, 12 Apr 2012 11:55:12 -0300, Mauro Carvalho Chehab
    <> wrote:
    > I can see only two viable fixes for it:
    > 1) add a typedef for the enum, using the sizeof(enum) in order to select
    > the
    > size of the used integer.
    > Pros:
    > - Patch is easy to write/easy to review;
    > - Won't change the struct size, so applications compiled without
    > strong gcc optimization won't break;
    > Cons:
    > - It will add a typedef, with is ugly;
    > - struct size on 32 bits will be different thant he size on 64 bits
    > (not really an issue, as v4l2-compat32 will handle that;

    On which platforms do enums occupy 64-bits? Alpha? More to the point, on
    which platform is enum not the same size as unsigned?

    At least on x86-64, enum is 32-bits and so is unsigned.

    > - v4l2-compat32 code may require changes.
    > 2) just replace it by a 32 bits integer.
    > Pros:
    > - no typedefs;
    > - struct size won't change between 32/64 bits (except when they also
    > have pointers);
    > Cons:
    > - will break ABI. So, a compat code is required;
    > - will require a "videodev2.h" fork for the legacy API with the enum's;
    > - will require a compat code to convert from enum into integer and
    > vice-versa.
    > Comments/Votes?

    Rémi Denis-Courmont
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      Last update: 2012-04-12 17:45    [W:0.021 / U:51.652 seconds]
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