--enable-kernel=VERSION compile for compatibility with kernel not older than VERSION
Code:
if test "$minimum_kernel" = yes || test "$minimum_kernel" = no; then
# Better nothing than this.
minimum_kernel=""
else
if test "$minimum_kernel" = current; then
minimum_kernel=`uname -r 2>/dev/null` || minimum_kernel=
fi
fi
And there we find a cross-compile bomb in the current eglibc configuration file.