kbuild: change kbuild to not rely on incorrect GNU make behavior
The kbuild system takes advantage of an incorrect behavior in GNU make.
Once this behavior is fixed, all files in the kernel rebuild every time,
even if nothing has changed. This patch ensures kbuild works with both
the incorrect and correct behaviors of GNU make.
For more details on the incorrect behavior, see:
http://lists.gnu.org/archive/html/bug-make/2006-03/msg00003.html
Changes in this patch:
- Keep all targets that are to be marked .PHONY in a variable, PHONY.
- Add .PHONY: $(PHONY) to mark them properly.
- Remove any $(PHONY) files from the $? list when determining whether
targets are up-to-date or not.
Signed-off-by: Paul Smith <psmith@gnu.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
diff --git a/Makefile b/Makefile
index 12c8d71..a59c1e2 100644
--- a/Makefile
+++ b/Makefile
@@ -95,7 +95,7 @@
endif
# That's our default target when none is given on the command line
-.PHONY: _all
+PHONY := _all
_all:
ifneq ($(KBUILD_OUTPUT),)
@@ -106,7 +106,7 @@
$(if $(KBUILD_OUTPUT),, \
$(error output directory "$(saved-output)" does not exist))
-.PHONY: $(MAKECMDGOALS)
+PHONY += $(MAKECMDGOALS)
$(filter-out _all,$(MAKECMDGOALS)) _all:
$(if $(KBUILD_VERBOSE:1=),@)$(MAKE) -C $(KBUILD_OUTPUT) \
@@ -123,7 +123,7 @@
# If building an external module we do not care about the all: rule
# but instead _all depend on modules
-.PHONY: all
+PHONY += all
ifeq ($(KBUILD_EXTMOD),)
_all: all
else
@@ -337,14 +337,14 @@
# Rules shared between *config targets and build targets
# Basic helpers built in scripts/
-.PHONY: scripts_basic
+PHONY += scripts_basic
scripts_basic:
$(Q)$(MAKE) $(build)=scripts/basic
# To avoid any implicit rule to kick in, define an empty command.
scripts/basic/%: scripts_basic ;
-.PHONY: outputmakefile
+PHONY += outputmakefile
# outputmakefile generate a Makefile to be placed in output directory, if
# using a seperate output directory. This allows convinient use
# of make in output directory
@@ -420,7 +420,7 @@
# Additional helpers built in scripts/
# Carefully list dependencies so we do not try to build scripts twice
# in parrallel
-.PHONY: scripts
+PHONY += scripts
scripts: scripts_basic include/config/MARKER
$(Q)$(MAKE) $(build)=$(@)
@@ -720,7 +720,7 @@
# make menuconfig etc.
# Error messages still appears in the original language
-.PHONY: $(vmlinux-dirs)
+PHONY += $(vmlinux-dirs)
$(vmlinux-dirs): prepare scripts
$(Q)$(MAKE) $(build)=$@
@@ -773,10 +773,10 @@
# version.h and scripts_basic is processed / created.
# Listed in dependency order
-.PHONY: prepare archprepare prepare0 prepare1 prepare2 prepare3
+PHONY += prepare archprepare prepare0 prepare1 prepare2 prepare3
# prepare-all is deprecated, use prepare as valid replacement
-.PHONY: prepare-all
+PHONY += prepare-all
# prepare3 is used to check if we are building in a separate output directory,
# and if so do:
@@ -857,7 +857,7 @@
# ---------------------------------------------------------------------------
-.PHONY: depend dep
+PHONY += depend dep
depend dep:
@echo '*** Warning: make $@ is unnecessary now.'
@@ -872,21 +872,21 @@
# Build modules
-.PHONY: modules
+PHONY += modules
modules: $(vmlinux-dirs) $(if $(KBUILD_BUILTIN),vmlinux)
@echo ' Building modules, stage 2.';
$(Q)$(MAKE) -rR -f $(srctree)/scripts/Makefile.modpost
# Target to prepare building external modules
-.PHONY: modules_prepare
+PHONY += modules_prepare
modules_prepare: prepare scripts
# Target to install modules
-.PHONY: modules_install
+PHONY += modules_install
modules_install: _modinst_ _modinst_post
-.PHONY: _modinst_
+PHONY += _modinst_
_modinst_:
@if [ -z "`$(DEPMOD) -V 2>/dev/null | grep module-init-tools`" ]; then \
echo "Warning: you may need to install module-init-tools"; \
@@ -913,7 +913,7 @@
else
depmod_opts := -b $(INSTALL_MOD_PATH) -r
endif
-.PHONY: _modinst_post
+PHONY += _modinst_post
_modinst_post: _modinst_
if [ -r System.map -a -x $(DEPMOD) ]; then $(DEPMOD) -ae -F System.map $(depmod_opts) $(KERNELRELEASE); fi
@@ -956,7 +956,7 @@
clean: rm-files := $(CLEAN_FILES)
clean-dirs := $(addprefix _clean_,$(srctree) $(vmlinux-alldirs))
-.PHONY: $(clean-dirs) clean archclean
+PHONY += $(clean-dirs) clean archclean
$(clean-dirs):
$(Q)$(MAKE) $(clean)=$(patsubst _clean_%,%,$@)
@@ -974,7 +974,7 @@
mrproper: rm-files := $(wildcard $(MRPROPER_FILES))
mrproper-dirs := $(addprefix _mrproper_,Documentation/DocBook scripts)
-.PHONY: $(mrproper-dirs) mrproper archmrproper
+PHONY += $(mrproper-dirs) mrproper archmrproper
$(mrproper-dirs):
$(Q)$(MAKE) $(clean)=$(patsubst _mrproper_%,%,$@)
@@ -984,7 +984,7 @@
# distclean
#
-.PHONY: distclean
+PHONY += distclean
distclean: mrproper
@find $(srctree) $(RCS_FIND_IGNORE) \
@@ -1000,7 +1000,7 @@
# rpm target kept for backward compatibility
package-dir := $(srctree)/scripts/package
-.PHONY: %-pkg rpm
+PHONY += %-pkg rpm
%pkg: FORCE
$(Q)$(MAKE) -f $(package-dir)/Makefile $@
@@ -1092,12 +1092,12 @@
# We are always building modules
KBUILD_MODULES := 1
-.PHONY: crmodverdir
+PHONY += crmodverdir
crmodverdir:
$(Q)rm -rf $(MODVERDIR)
$(Q)mkdir -p $(MODVERDIR)
-.PHONY: $(objtree)/Module.symvers
+PHONY += $(objtree)/Module.symvers
$(objtree)/Module.symvers:
@test -e $(objtree)/Module.symvers || ( \
echo; \
@@ -1106,7 +1106,7 @@
echo )
module-dirs := $(addprefix _module_,$(KBUILD_EXTMOD))
-.PHONY: $(module-dirs) modules
+PHONY += $(module-dirs) modules
$(module-dirs): crmodverdir $(objtree)/Module.symvers
$(Q)$(MAKE) $(build)=$(patsubst _module_%,%,$@)
@@ -1114,11 +1114,11 @@
@echo ' Building modules, stage 2.';
$(Q)$(MAKE) -rR -f $(srctree)/scripts/Makefile.modpost
-.PHONY: modules_install
+PHONY += modules_install
modules_install: _emodinst_ _emodinst_post
-install-dir := $(if $(INSTALL_MOD_DIR),$(INSTALL_MOD_DIR),extra)
-.PHONY: _emodinst_
+install-dir := $(if $(INSTALL_MOD_DIR),$(INSTALL_MOD_DIR),extra)
+PHONY += _emodinst_
_emodinst_:
$(Q)rm -rf $(MODLIB)/$(install-dir)
$(Q)mkdir -p $(MODLIB)/$(install-dir)
@@ -1133,13 +1133,13 @@
$(KERNELRELEASE); \
fi
-.PHONY: _emodinst_post
+PHONY += _emodinst_post
_emodinst_post: _emodinst_
$(call cmd,depmod)
clean-dirs := $(addprefix _clean_,$(KBUILD_EXTMOD))
-.PHONY: $(clean-dirs) clean
+PHONY += $(clean-dirs) clean
$(clean-dirs):
$(Q)$(MAKE) $(clean)=$(patsubst _clean_%,%,$@)
@@ -1161,7 +1161,7 @@
@echo ''
# Dummies...
-.PHONY: prepare scripts
+PHONY += prepare scripts
prepare: ;
scripts: ;
endif # KBUILD_EXTMOD
@@ -1274,7 +1274,7 @@
endif #ifeq ($(config-targets),1)
endif #ifeq ($(mixed-targets),1)
-.PHONY: checkstack
+PHONY += checkstack
checkstack:
$(OBJDUMP) -d vmlinux $$(find . -name '*.ko') | \
$(PERL) $(src)/scripts/checkstack.pl $(ARCH)
@@ -1357,4 +1357,10 @@
endif # skip-makefile
+PHONY += FORCE
FORCE:
+
+
+# Declare the contents of the .PHONY variable as phony. We keep that
+# information in a variable se we can use it in if_changed and friends.
+.PHONY: $(PHONY)