+ # On Linux libudev is currently required for enumeration.
+ AC_ARG_WITH([libudev],
+ [AS_HELP_STRING([--with-libudev],
+ [use libudev for serial port enumeration @<:@default=check@:>@])],
+ [], [with_libudev=check])
+ AS_IF([test "x$with_libudev" != xno], [