make USE_INET6=YES a default, if the package is compiled on IPv6-ready

userland (checked by existence of /sbin/ping6).

with the change, the default value for USE_INET6 will be like this:
- non-NetBSD: undefined
- NetBSD releases prior and including 1.4.x: undefined
- NetBSD-current (pre-1.5) prior to IPv6 integration: undefined
- NetBSD-current after IPv6 integration: USE_INET6=YES

It is advised to obey the default.

2 files changed, 15 insertions, 6 deletions

diff --git a/mk/bsd.prefs.mk b/mk/bsd.prefs.mk
index da053f199bc..394f6922fdc 100644
--- a/mk/bsd.prefs.mk
+++ b/mk/bsd.prefs.mk
@@ -1,4 +1,4 @@
-# $NetBSD: bsd.prefs.mk,v 1.13 1999/09/18 15:33:55 kim Exp $
+# $NetBSD: bsd.prefs.mk,v 1.14 2000/01/24 07:04:28 itojun Exp $
 #
 # Make file, included to get the site preferences, if any.  Should
 # only be included by package Makefiles before any .if defined()
@@ -92,6 +92,11 @@ MAKE_ENV+=		EXTRA_SYS_MK_INCLUDES="<bsd.own.mk>"
 	@${FALSE}
 .endif
 
+# if the system is IPv6-ready NetBSD, compile with IPv6 support turned on.
+.if (${OPSYS} == "NetBSD") && exists(/sbin/ping6)
+USE_INET6?=		YES
+.endif
+
 # Preload all default values for CFLAGS, LDFLAGS, etc. before bsd.pkg.mk
 # or a pkg Makefile modifies them.
 .include <sys.mk>
diff --git a/mk/mk.conf.example b/mk/mk.conf.example
index 8f0b309ab0e..ff22592290d 100644
--- a/mk/mk.conf.example
+++ b/mk/mk.conf.example
@@ -1,4 +1,4 @@
-# $NetBSD: mk.conf.example,v 1.118 2000/01/23 02:30:26 wiz Exp $
+# $NetBSD: mk.conf.example,v 1.119 2000/01/24 07:04:28 itojun Exp $
 #
 
 # Sample /etc/mk.conf file, which can be used to set specific values
@@ -563,10 +563,14 @@ PAPERSIZE=	A4
 # Default: package-dependent
 
 #USE_INET6=
-# Enable IPv6 support on certain packages.  Use IPv6-ready kernel if
-# you define this.
-# Possible: not defined, YES
-# Default: not defined
+# Enable IPv6 support on certain packages.  It is safer to leave it undefined
+# in mk.conf and obey the default.  Reasons:
+# - it is just fine to use IPv6-ready packages on top of non-IPv6 kernel
+#   (assuming that you have IPv6-ready headers and libraries)
+# - it may cause some trouble to use a package compiled with USE_INET6=NO,
+#   on top of IPv6-ready kernel
+# Possible: not defined, NO, YES
+# Default: YES on IPv6-ready userland, not defined otherwise
 
 #USE_INN=
 # Used in trn and nn to specify use of "inn" instead of "nntpclnt"