> +# > +# Check if asm/mman.h can be included > +# > +AC_DEFUN([AC_HAVE_KERNEL_MADVISE_FLAGS], > + [ AC_MSG_CHECKING([for kernel madvise flags in asm/mman.h ]) > + AC_COMPILE_IFELSE( > + [ AC_LANG_PROGRAM([[ > +#include <asm/mman.h> > + ]], [[ > +int moo = MADV_COLLAPSE; > + ]]) > + ], have_kernel_madvise=yes > + AC_MSG_RESULT(yes), > + AC_MSG_RESULT(no)) > + AC_SUBST(have_kernel_madvise) > + ]) > + I don't think we really need this check, as madvise and asm/mman.h have been around forever. We can probably also drop most of the actual flag idefs, probably for everything older than MADV_WIPEONFORK. The rest looks good to me.