Index: bsd.port.mk
===================================================================
RCS file: /home/amdmi3/projects/freebsd/FreeBSD.cvs/ports/Mk/bsd.port.mk,v
retrieving revision 1.654
diff -u -r1.654 bsd.port.mk
--- bsd.port.mk	8 Nov 2010 16:07:03 -0000	1.654
+++ bsd.port.mk	9 Nov 2010 20:33:22 -0000
@@ -323,6 +323,14 @@
 #					'yes'		as a library dependency
 #					'run'		as a run-time dependency
 ##
+# USE_SRC       - If set, this port requires system sources installed
+# SRC_BASE      - Set to path to system sources.
+#                 Default: /usr/src
+# DISABLE_SRC_VERSION_CHECK
+#               - Set by user to disable check for that sources and
+#                 system version match (use on your own risk).
+#                 Default: not set
+##
 # USE_PERL5		- If set, this port uses perl5 in one or more of the extract,
 #				  patch, build, install or run phases.
 # USE_PERL5_BUILD
@@ -1216,12 +1224,14 @@
 OSREL!=	${UNAME} -r | ${SED} -e 's/[-(].*//'
 .endif
 
+SRC_BASE?=	/usr/src
+
 # Get __FreeBSD_version
 .if !defined(OSVERSION)
 .if exists(/usr/include/sys/param.h)
 OSVERSION!=	${AWK} '/^\#define[[:blank:]]__FreeBSD_version/ {print $$3}' < /usr/include/sys/param.h
 .elif exists(/usr/src/sys/sys/param.h)
-OSVERSION!=	${AWK} '/^\#define[[:blank::]]__FreeBSD_version/ {print $$3}' < /usr/src/sys/sys/param.h
+OSVERSION!=	${AWK} '/^\#define[[:blank:]]__FreeBSD_version/ {print $$3}' < /usr/src/sys/sys/param.h
 .else
 OSVERSION!=	${SYSCTL} -n kern.osreldate
 .endif
@@ -2311,6 +2321,16 @@
 PTHREAD_CFLAGS?=
 PTHREAD_LIBS?=		-pthread
 
+.if defined(USE_SRC)
+.	if !exists(${SRC_BASE}/sys/sys/param.h)
+IGNORE=		requires system sources installed
+.	endif
+SRCVERSION!=	${AWK} '/^\#define[[:blank:]]__FreeBSD_version/ {print $$3}' < ${SRC_BASE}/sys/sys/param.h
+.	if !defined(DISABLE_SRC_VERSION_CHECK) && ${SRCVERSION} != ${OSVERSION}
+IGNORE=		the version of system sources at ${SRC_BASE} doesn't match with your system version
+.	endif
+.endif
+
 .if exists(/usr/bin/fetch)
 FETCH_BINARY?=	/usr/bin/fetch
 FETCH_ARGS?=	-ApRr