diff --git a/BitKeeper/etc/ignore b/BitKeeper/etc/ignore
index 723303c1ba..a5583563b1 100644
--- a/BitKeeper/etc/ignore
+++ b/BitKeeper/etc/ignore
@@ -58,6 +58,7 @@ netbsd-*-tools/*
 netbsd-*-xen0/*
 netbsd-*-xenU/*
 netbsd-*.patch
+patches/*/.makedep
 patches/ebtables-brnf-5_vs_2.4.25.diff
 patches/ebtables.diff
 patches/tmp/*
diff --git a/Makefile b/Makefile
index 7b468d1723..7e589f098c 100644
--- a/Makefile
+++ b/Makefile
@@ -15,8 +15,6 @@ KERNELS ?= linux-2.6-xen0 linux-2.6-xenU
 # linux-2.4-xen0 linux-2.4-xenU netbsd-2.0-xenU
 # You may use wildcards in the above e.g. KERNELS=*2.4*
 
-ALLKERNELS = $(patsubst buildconfigs/mk.%,%,$(wildcard buildconfigs/mk.*))
-ALLSPARSETREES = $(patsubst %-xen-sparse,%,$(wildcard *-xen-sparse))
 XKERNELS := $(foreach kernel, $(KERNELS), $(patsubst buildconfigs/mk.%,%,$(wildcard buildconfigs/mk.$(kernel))) )
 
 export DESTDIR
@@ -87,7 +85,7 @@ world:
 	$(MAKE) dist
 
 # clean doesn't do a kclean
-clean: 
+clean:: 
 	$(MAKE) -C xen clean
 	$(MAKE) -C tools clean
 	$(MAKE) -C docs clean
diff --git a/buildconfigs/Rules.mk b/buildconfigs/Rules.mk
index 11f4009525..1e65484b36 100644
--- a/buildconfigs/Rules.mk
+++ b/buildconfigs/Rules.mk
@@ -6,6 +6,9 @@ include Config.mk
 DISTDIR	?= $(CURDIR)/dist
 DESTDIR	?= $(DISTDIR)/install
 
+ALLKERNELS = $(patsubst buildconfigs/mk.%,%,$(wildcard buildconfigs/mk.*))
+ALLSPARSETREES = $(patsubst %-xen-sparse,%,$(wildcard *-xen-sparse))
+
 .PHONY:	mkpatches mrproper
 
 # Setup pristine search path
@@ -49,24 +52,30 @@ else
 OS_VER = $(NETBSD_VER)
 endif
 
-pristine-%: %.tar.bz2
-	rm -rf tmp-$(@F) $@
-	mkdir -p tmp-$(@F)
-	tar -C tmp-$(@F) -jxf $<
-	mv tmp-$(@F)/* $@
-	touch $@ # update timestamp to avoid rebuild
+$(patsubst %,pristine-%/.valid-pristine,$(ALLSPARSETREES)) : pristine-%/.valid-pristine: %.tar.bz2
+	rm -rf tmp-pristine-$* $(@D)
+	mkdir -p tmp-pristine-$*
 	touch $@/.bk_skip
-	@rm -rf tmp-$(@F)
+	tar -C tmp-pristine-$* -jxf $<
+	mv tmp-pristine-$*/* $(@D)
+	@rm -rf tmp-pristine-$*
+	touch $@ # update timestamp to avoid rebuild
 
-OS_PATCHES = $(shell echo patches/$(OS)-$(OS_VER)/*.patch)
+PATCHDIRS := $(wildcard patches/*-*)
 
-ref-%: pristine-% $(OS_PATCHES)
-	rm -rf $@
-	cp -al $< tmp-$(@F)
+-include $(patsubst %,%/.makedep,$(PATCHDIRS))
+
+$(patsubst patches/%,patches/%/.makedep,$(PATCHDIRS)): patches/%/.makedep: 
+	@echo 'ref-$*/.valid-ref: $$(wildcard patches/$*/*.patch)' >$@
+
+clean::
+	rm -f patches/*/.makedep
+
+ref-%/.valid-ref: pristine-%/.valid-pristine
+	rm -rf $(@D)
+	cp -al $(<D) $(@D)
 	[ -d patches/$* ] && \
-	  for i in patches/$*/*.patch ; do ( cd tmp-$(@F) ; patch -p1 <../$$i ) ; done || \
-	  true
-	mv tmp-$(@F) $@
+	  for i in patches/$*/*.patch ; do ( cd $(@D) ; patch -p1 <../$$i || exit 1 ) ; done
 	touch $@ # update timestamp to avoid rebuild
 
 %-build:
@@ -81,11 +90,11 @@ ref-%: pristine-% $(OS_PATCHES)
 %-config:
 	$(MAKE) -f buildconfigs/mk.$* config
 
-%-xen.patch: ref-%
+%-xen.patch: ref-%/.valid-ref
 	rm -rf tmp-$@
-	cp -al $< tmp-$@
+	cp -al $(<D) tmp-$@
 	( cd $*-xen-sparse && ./mkbuildtree ../tmp-$@ )	
-	diff -Nurp $< tmp-$@ > $@ || true
+	diff -Nurp $(<D) tmp-$@ > $@ || true
 	rm -rf tmp-$@
 
 %-mrproper: %-mrproper-extra
diff --git a/buildconfigs/mk.linux-2.4-xen0 b/buildconfigs/mk.linux-2.4-xen0
index e28b3a1981..6044268d09 100644
--- a/buildconfigs/mk.linux-2.4-xen0
+++ b/buildconfigs/mk.linux-2.4-xen0
@@ -24,9 +24,9 @@ patches/tmp/ebtables.diff:
 	wget http://www.cl.cam.ac.uk/netos/xen/downloads/ebtables-brnf-5_vs_2.4.27.diff.gz -O- | gunzip -c > $@
 
 $(LINUX_DIR)/include/linux/autoconf.h: patches/tmp/ebtables.diff
-$(LINUX_DIR)/include/linux/autoconf.h: ref-$(OS)-$(LINUX_VER)
+$(LINUX_DIR)/include/linux/autoconf.h: ref-$(OS)-$(LINUX_VER)/.valid-ref
 	rm -rf $(LINUX_DIR)
-	cp -al $< $(LINUX_DIR)
+	cp -al $(<D) $(LINUX_DIR)
 	# Apply arch-xen patches
 	( cd linux-$(LINUX_VER)-xen-sparse ; \
           ./mkbuildtree ../$(LINUX_DIR) )
@@ -50,7 +50,7 @@ config: $(LINUX_DIR)/include/linux/autoconf.h
 	$(MAKE) -C $(LINUX_DIR) ARCH=xen $(CONFIGMODE)
 	$(MAKE) -C $(LINUX_DIR) ARCH=xen dep
 
-clean:
+clean::
 	$(MAKE) -C $(LINUX_DIR) ARCH=xen clean
 
 delete: 
diff --git a/buildconfigs/mk.linux-2.4-xenU b/buildconfigs/mk.linux-2.4-xenU
index 9205c26776..4975a98892 100644
--- a/buildconfigs/mk.linux-2.4-xenU
+++ b/buildconfigs/mk.linux-2.4-xenU
@@ -19,9 +19,9 @@ build: $(LINUX_DIR)/include/linux/autoconf.h
 	fi
 	$(MAKE) -C $(LINUX_DIR) ARCH=xen INSTALL_PATH=$(DESTDIR) install
 
-$(LINUX_DIR)/include/linux/autoconf.h: ref-linux-$(LINUX_VER)
+$(LINUX_DIR)/include/linux/autoconf.h: ref-linux-$(LINUX_VER)/.valid-ref
 	rm -rf $(LINUX_DIR)
-	cp -al $< $(LINUX_DIR)
+	cp -al $(<D) $(LINUX_DIR)
 	# Apply arch-xen patches
 	( cd linux-$(LINUX_VER)-xen-sparse ; \
           ./mkbuildtree ../$(LINUX_DIR) )
@@ -43,7 +43,7 @@ config: $(LINUX_DIR)/include/linux/autoconf.h
 	$(MAKE) -C $(LINUX_DIR) ARCH=xen $(CONFIGMODE)
 	$(MAKE) -C $(LINUX_DIR) ARCH=xen dep
 
-clean:
+clean::
 	$(MAKE) -C $(LINUX_DIR) ARCH=xen clean
 
 delete: 
diff --git a/buildconfigs/mk.linux-2.6-xen0 b/buildconfigs/mk.linux-2.6-xen0
index cfba1824b0..d238a10630 100644
--- a/buildconfigs/mk.linux-2.6-xen0
+++ b/buildconfigs/mk.linux-2.6-xen0
@@ -19,9 +19,9 @@ build: $(LINUX_DIR)/include/linux/autoconf.h
 	fi
 	$(MAKE) -C $(LINUX_DIR) ARCH=xen INSTALL_PATH=$(DESTDIR) install
 
-$(LINUX_DIR)/include/linux/autoconf.h: ref-$(OS)-$(LINUX_VER)
+$(LINUX_DIR)/include/linux/autoconf.h: ref-$(OS)-$(LINUX_VER)/.valid-ref
 	rm -rf $(LINUX_DIR)
-	cp -al $< $(LINUX_DIR)
+	cp -al $(<D) $(LINUX_DIR)
 	# Apply arch-xen patches
 	( cd linux-$(LINUX_VER)-xen-sparse ; \
           ./mkbuildtree ../$(LINUX_DIR) )
@@ -41,7 +41,7 @@ config: CONFIGMODE = menuconfig
 config: $(LINUX_DIR)/include/linux/autoconf.h
 	$(MAKE) -C $(LINUX_DIR) ARCH=xen $(CONFIGMODE)
 
-clean:
+clean::
 	$(MAKE) -C $(LINUX_DIR) ARCH=xen clean
 
 delete: 
diff --git a/buildconfigs/mk.linux-2.6-xenU b/buildconfigs/mk.linux-2.6-xenU
index f2df01f9a7..6101664db1 100644
--- a/buildconfigs/mk.linux-2.6-xenU
+++ b/buildconfigs/mk.linux-2.6-xenU
@@ -19,9 +19,9 @@ build: $(LINUX_DIR)/include/linux/autoconf.h
 	fi
 	$(MAKE) -C $(LINUX_DIR) ARCH=xen INSTALL_PATH=$(DESTDIR) install
 
-$(LINUX_DIR)/include/linux/autoconf.h: ref-$(OS)-$(LINUX_VER)
+$(LINUX_DIR)/include/linux/autoconf.h: ref-$(OS)-$(LINUX_VER)/.valid-ref
 	rm -rf $(LINUX_DIR)
-	cp -al $< $(LINUX_DIR)
+	cp -al $(<D) $(LINUX_DIR)
 	# Apply arch-xen patches
 	( cd linux-$(LINUX_VER)-xen-sparse ; \
           ./mkbuildtree ../$(LINUX_DIR) )
@@ -41,7 +41,7 @@ config: CONFIGMODE = menuconfig
 config: $(LINUX_DIR)/include/linux/autoconf.h
 	$(MAKE) -C $(LINUX_DIR) ARCH=xen $(CONFIGMODE)
 
-clean:
+clean::
 	$(MAKE) -C $(LINUX_DIR) ARCH=xen clean
 
 delete: 
diff --git a/buildconfigs/mk.netbsd-2.0-xenU b/buildconfigs/mk.netbsd-2.0-xenU
index bbe2e1fea9..d5a740d0c3 100644
--- a/buildconfigs/mk.netbsd-2.0-xenU
+++ b/buildconfigs/mk.netbsd-2.0-xenU
@@ -24,9 +24,9 @@ netbsd-%-tools: netbsd-%-tools.tar.bz2
 	tar -jxf $<
 	touch $@ # update timestamp to avoid rebuild
 
-$(NETBSD_DIR)/.valid: ref-$(OS)-$(NETBSD_VER)
+$(NETBSD_DIR)/.valid: ref-$(OS)-$(NETBSD_VER)/.valid-ref
 	$(RM) -rf $(NETBSD_DIR)
-	cp -al $< $(NETBSD_DIR)
+	cp -al $(<D) $(NETBSD_DIR)
 	# Apply arch-xen patches
 	( cd netbsd-$(NETBSD_VER)-xen-sparse ; \
           ./mkbuildtree ../$(NETBSD_DIR) )
@@ -38,7 +38,7 @@ netbsd-xen%: $(NETBSD_DIR)/.valid netbsd-$(NETBSD_RELEASE)-tools
 	$(MAKE) -C netbsd-$(FULLVERSION) netbsd
 	$(MAKE) -C netbsd-$(FULLVERSION) INSTALL_PATH=$(DESTDIR) INSTALL_NAME=boot/netbsd-$(NETBSD_VER)-xen$* install
 
-clean:
+clean::
 	$(MAKE) -C netbsd-$(FULLVERSION) clean
 
 delete: