The time is not yet ripe to break the lack of dependencies between

src/sys and the rest of the tree for builds.
o eliminate including bsd.mkopts.mk for the moment in kern.opts.mk
o No need to include src.opts.mk at all anymore. The reasons for it
  are now coverted in sys.mk and src.sys.mk.

share/mk/src.sys.mk

@@ -1,7 +1,13 @@
 # $FreeBSD$
 
+# Note: This file is also duplicated in the sys/conf/kern.pre.mk so
+# it will always grab SRCCONF, even if it isn't being built in-tree
+# to preserve historical (and useful) behavior. Changes here need to
+# be reflected there so SRCCONF isn't included multiple times.
+
 # Allow user to configure things that only effect src tree builds.
 SRCCONF?=	/etc/src.conf
-.if exists(${SRCCONF}) || ${SRCCONF} != "/etc/src.conf"
+.if (exists(${SRCCONF}) || ${SRCCONF} != "/etc/src.conf") && !target(_srcconf_included_)
 .include "${SRCCONF}"
+_srcconf_included_:
 .endif

sys/conf/kern.opts.mk

@@ -19,17 +19,15 @@ __DEFAULT_YES_OPTIONS = \
     FORMAT_EXTENSIONS \
     KERNEL_SYMBOLS
 
-__DEFAULT_NO_OPTIONS = \
+# expanded inline from bsd.mkopt.mk:
 
-# Kludge to allow a less painful transition. If MAKESYSPATH isn't defined,
+.for var in ${__DEFAULT_YES_OPTIONS}
-# assume we have a standard FreeBSD src tree layout and reach over and grab
+.if !defined(MK_${var})
-# bsd.mkopt.mk from there. If it is defined, trust it to point someplace sane
+.if defined(WITHOUT_${var})			# WITHOUT always wins
-# and include bsd.mkopt.mk from there. We need the !defined case to keep ports
+MK_${var}:=	no
-# kernel modules working (though arguably they should define MAKESYSPATH). We
-# need the latter case to keep the Jenkins testing harness working where they
-# specifically use a non-standard layout, but do define MAKESYSPATH correctly.
-.if !defined(MAKESYSPATH)
-.include "../../share/mk/bsd.mkopt.mk"
 .else
-.include <bsd.mkopt.mk>
+MK_${var}:=	yes
 .endif
+.endif
+.endfor
+.undef __DEFAULT_YES_OPTIONS

sys/conf/kern.pre.mk

@@ -3,7 +3,19 @@
 # Part of a unified Makefile for building kernels.  This part contains all
 # of the definitions that need to be before %BEFORE_DEPEND.
 
-.include <src.opts.mk>
+# Allow user to configure things that only effect src tree builds.
+# Note: This is duplicated from src.sys.mk to ensure that we include
+# /etc/src.conf when building the kernel. Kernels can be built without
+# the rest of /usr/src, but they still always process SRCCONF even though
+# the normal mechanisms to prevent that (compiling out of tree) won't
+# work. To ensure they do work, we have to duplicate thee few lines here.
+SRCCONF?=	/etc/src.conf
+.if (exists(${SRCCONF}) || ${SRCCONF} != "/etc/src.conf") && !target(_srcconf_included_)
+.include "${SRCCONF}"
+_srcconf_included_:
+.endif
+
+.include <bsd.own.mk>
 .include <bsd.compiler.mk>
 .include "kern.opts.mk"
 

sys/conf/kmod.mk

@@ -65,15 +65,10 @@ KMODLOAD?=	/sbin/kldload
 KMODUNLOAD?=	/sbin/kldunload
 OBJCOPY?=	objcopy
 
-# Note: we're really bsd.kmod.mk, so we have to allow src.opts.mk to be
+# Grab all the options for a kernel build.
-# optional. Include it if we can so we can get /etc/src.conf changes,
+.include "kern.opts.mk"
-# if we're in the tree. If we can't include it that's OK. kern.opts.mk
-# has all the kernel options in it, and should be included after src.opts.mk
-# so it picks everything up.
-.sinclude <src.opts.mk>
 .include <bsd.init.mk>
 .include <bsd.compiler.mk>
-.include "kern.opts.mk"
 
 .SUFFIXES: .out .o .c .cc .cxx .C .y .l .s .S