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    SubjectRe: RFC: Testing for kernel features in external modules
    On Jun 24, 2004  22:30 +0200, Sam Ravnborg wrote:
    > +if [ -f remap4.o ]; then
    > + echo "#define REMAP4 1" > $2
    > +elif [ -f remap5.o ]; then
    > + echo "#define REMAP5 1" > $2
    > +fi

    I would prefer that these be called something like HAVE_REMAP5, or
    better yet something descriptive like HAVE_REMAP_PAGE_RANGE_VMA.

    This obviously needs to be smarter also, to handle adding multiple
    #defines to a single .h file.

    Ideally, when people make an incompatible kernel API change like this
    they would just #define HAVE_REMAP_PAGE_RANGE_VMA in the header that
    declares remap_page_range() directly (e.g. KERNEL_AS_O_DIRECT was added
    for this reason) instead of external builds having to figure this out
    themselves. Adding the check script is no less work than just adding
    the #define to the appropriate header directly.

    Having something like "features.h" is only useful as far as it checks
    for features that applications care about. If it doesn't have checks
    for features, then the apps need to implement those checks anyways
    and different apps will name the script/#define differently so until
    they make it into the stock kernel it isn't terribly useful.

    Cheers, Andreas
    Andreas Dilger

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      Last update: 2005-03-22 14:04    [W:0.021 / U:18.372 seconds]
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