* [PATCH] kbuild: drop FORCE from PHONY targets @ 2016-03-13 0:13 Masahiro Yamada 2016-03-14 0:39 ` Andy Lutomirski 2016-04-20 8:29 ` Michal Marek 0 siblings, 2 replies; 12+ messages in thread From: Masahiro Yamada @ 2016-03-13 0:13 UTC (permalink / raw) To: linux-kbuild Cc: Masahiro Yamada, Tony Luck, Nathan Lynch, linux-ia64, Michal Marek, x86, H. Peter Anvin, linux-kernel, Thomas Gleixner, Russell King, Andy Lutomirski, Ingo Molnar, Fenghua Yu, linux-arm-kernel These targets are marked as PHONY. No need to add FORCE to their dependency. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> --- Makefile | 8 ++++---- arch/arm/vdso/Makefile | 2 +- arch/ia64/Makefile | 4 ++-- arch/x86/entry/vdso/Makefile | 4 ++-- 4 files changed, 9 insertions(+), 9 deletions(-) diff --git a/Makefile b/Makefile index 2d519d2..e3ef6b6 100644 --- a/Makefile +++ b/Makefile @@ -142,7 +142,7 @@ PHONY += $(MAKECMDGOALS) sub-make $(filter-out _all sub-make $(CURDIR)/Makefile, $(MAKECMDGOALS)) _all: sub-make @: -sub-make: FORCE +sub-make: $(Q)$(MAKE) -C $(KBUILD_OUTPUT) KBUILD_SRC=$(CURDIR) \ -f $(CURDIR)/Makefile $(filter-out _all sub-make,$(MAKECMDGOALS)) @@ -989,7 +989,7 @@ prepare1: prepare2 $(version_h) include/generated/utsrelease.h \ archprepare: archheaders archscripts prepare1 scripts_basic -prepare0: archprepare FORCE +prepare0: archprepare $(Q)$(MAKE) $(build)=. # All the preparing.. @@ -1034,7 +1034,7 @@ INSTALL_FW_PATH=$(INSTALL_MOD_PATH)/lib/firmware export INSTALL_FW_PATH PHONY += firmware_install -firmware_install: FORCE +firmware_install: @mkdir -p $(objtree)/firmware $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.fwinst obj=firmware __fw_install @@ -1054,7 +1054,7 @@ PHONY += archscripts archscripts: PHONY += __headers -__headers: $(version_h) scripts_basic asm-generic archheaders archscripts FORCE +__headers: $(version_h) scripts_basic asm-generic archheaders archscripts $(Q)$(MAKE) $(build)=scripts build_unifdef PHONY += headers_install_all diff --git a/arch/arm/vdso/Makefile b/arch/arm/vdso/Makefile index 1160434..59a8fa7 100644 --- a/arch/arm/vdso/Makefile +++ b/arch/arm/vdso/Makefile @@ -74,5 +74,5 @@ $(MODLIB)/vdso: FORCE @mkdir -p $(MODLIB)/vdso PHONY += vdso_install -vdso_install: $(obj)/vdso.so.dbg $(MODLIB)/vdso FORCE +vdso_install: $(obj)/vdso.so.dbg $(MODLIB)/vdso $(call cmd,vdso_install) diff --git a/arch/ia64/Makefile b/arch/ia64/Makefile index 970d0bd..648f1ce 100644 --- a/arch/ia64/Makefile +++ b/arch/ia64/Makefile @@ -95,8 +95,8 @@ define archhelp echo '* unwcheck - Check vmlinux for invalid unwind info' endef -archprepare: make_nr_irqs_h FORCE +archprepare: make_nr_irqs_h PHONY += make_nr_irqs_h FORCE -make_nr_irqs_h: FORCE +make_nr_irqs_h: $(Q)$(MAKE) $(build)=arch/ia64/kernel include/generated/nr-irqs.h diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile index c854541..a81b539 100644 --- a/arch/x86/entry/vdso/Makefile +++ b/arch/x86/entry/vdso/Makefile @@ -188,10 +188,10 @@ vdso_img_insttargets := $(vdso_img_sodbg:%.dbg=install_%) $(MODLIB)/vdso: FORCE @mkdir -p $(MODLIB)/vdso -$(vdso_img_insttargets): install_%: $(obj)/%.dbg $(MODLIB)/vdso FORCE +$(vdso_img_insttargets): install_%: $(obj)/%.dbg $(MODLIB)/vdso $(call cmd,vdso_install) PHONY += vdso_install $(vdso_img_insttargets) -vdso_install: $(vdso_img_insttargets) FORCE +vdso_install: $(vdso_img_insttargets) clean-files := vdso32.so vdso32.so.dbg vdso64* vdso-image-*.c vdsox32.so* -- 1.9.1 ^ permalink raw reply related [flat|nested] 12+ messages in thread
* Re: [PATCH] kbuild: drop FORCE from PHONY targets 2016-03-13 0:13 [PATCH] kbuild: drop FORCE from PHONY targets Masahiro Yamada @ 2016-03-14 0:39 ` Andy Lutomirski 2016-03-14 4:08 ` Masahiro Yamada 2016-04-20 8:29 ` Michal Marek 1 sibling, 1 reply; 12+ messages in thread From: Andy Lutomirski @ 2016-03-14 0:39 UTC (permalink / raw) To: Masahiro Yamada Cc: Fenghua Yu, Thomas Gleixner, Ingo Molnar, Russell King, Michal Marek, linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, Nathan Lynch, Tony Luck, linux-ia64@vger.kernel.org, linux-arm-kernel@lists.infradead.org, H. Peter Anvin, X86 ML On Mar 12, 2016 4:14 PM, "Masahiro Yamada" <yamada.masahiro@socionext.com> wrote: > > These targets are marked as PHONY. No need to add FORCE to their > dependency. If this is, in fact, correct, can you update Documentation/kbuild/makefiles.txt as well? Thanks, Andy ^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] kbuild: drop FORCE from PHONY targets 2016-03-14 0:39 ` Andy Lutomirski @ 2016-03-14 4:08 ` Masahiro Yamada 2016-03-14 4:28 ` Andy Lutomirski 0 siblings, 1 reply; 12+ messages in thread From: Masahiro Yamada @ 2016-03-14 4:08 UTC (permalink / raw) To: Andy Lutomirski Cc: Fenghua Yu, Thomas Gleixner, Ingo Molnar, Russell King, Michal Marek, linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, Nathan Lynch, Tony Luck, linux-ia64@vger.kernel.org, linux-arm-kernel@lists.infradead.org, H. Peter Anvin, X86 ML Hi Andy 2016-03-14 9:39 GMT+09:00 Andy Lutomirski <luto@amacapital.net>: > On Mar 12, 2016 4:14 PM, "Masahiro Yamada" > <yamada.masahiro@socionext.com> wrote: >> >> These targets are marked as PHONY. No need to add FORCE to their >> dependency. > > If this is, in fact, correct, can you update > Documentation/kbuild/makefiles.txt as well? Which line do you want me to update? -- Best Regards Masahiro Yamada ^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] kbuild: drop FORCE from PHONY targets 2016-03-14 4:08 ` Masahiro Yamada @ 2016-03-14 4:28 ` Andy Lutomirski 2016-03-14 4:36 ` Masahiro Yamada 0 siblings, 1 reply; 12+ messages in thread From: Andy Lutomirski @ 2016-03-14 4:28 UTC (permalink / raw) To: Masahiro Yamada Cc: Fenghua Yu, Thomas Gleixner, Ingo Molnar, Russell King, Michal Marek, linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, Nathan Lynch, Tony Luck, linux-ia64@vger.kernel.org, linux-arm-kernel@lists.infradead.org, H. Peter Anvin, X86 ML On Sun, Mar 13, 2016 at 9:08 PM, Masahiro Yamada <yamada.masahiro@socionext.com> wrote: > > Hi Andy > > 2016-03-14 9:39 GMT+09:00 Andy Lutomirski <luto@amacapital.net>: > > On Mar 12, 2016 4:14 PM, "Masahiro Yamada" > > <yamada.masahiro@socionext.com> wrote: > >> > >> These targets are marked as PHONY. No need to add FORCE to their > >> dependency. > > > > If this is, in fact, correct, can you update > > Documentation/kbuild/makefiles.txt as well? > > Which line do you want me to update? > All the references to FORCE should probably mention .PHONY as an alternative. --Andy > > > > > -- > Best Regards > Masahiro Yamada -- Andy Lutomirski AMA Capital Management, LLC ^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] kbuild: drop FORCE from PHONY targets 2016-03-14 4:28 ` Andy Lutomirski @ 2016-03-14 4:36 ` Masahiro Yamada 2016-03-14 4:44 ` Andy Lutomirski 0 siblings, 1 reply; 12+ messages in thread From: Masahiro Yamada @ 2016-03-14 4:36 UTC (permalink / raw) To: Andy Lutomirski Cc: Fenghua Yu, Thomas Gleixner, Ingo Molnar, Russell King, Michal Marek, linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, Nathan Lynch, Tony Luck, linux-ia64@vger.kernel.org, linux-arm-kernel@lists.infradead.org, H. Peter Anvin, X86 ML 2016-03-14 13:28 GMT+09:00 Andy Lutomirski <luto@amacapital.net>: > On Sun, Mar 13, 2016 at 9:08 PM, Masahiro Yamada > <yamada.masahiro@socionext.com> wrote: >> >> Hi Andy >> >> 2016-03-14 9:39 GMT+09:00 Andy Lutomirski <luto@amacapital.net>: >> > On Mar 12, 2016 4:14 PM, "Masahiro Yamada" >> > <yamada.masahiro@socionext.com> wrote: >> >> >> >> These targets are marked as PHONY. No need to add FORCE to their >> >> dependency. >> > >> > If this is, in fact, correct, can you update >> > Documentation/kbuild/makefiles.txt as well? >> >> Which line do you want me to update? >> > > All the references to FORCE should probably mention .PHONY as an alternative. I do not get your point. All the examples in the makefile.txt correctly reference to FORCE. They are not PHONY targets. No need to update. -- Best Regards Masahiro Yamada ^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] kbuild: drop FORCE from PHONY targets 2016-03-14 4:36 ` Masahiro Yamada @ 2016-03-14 4:44 ` Andy Lutomirski 2016-03-14 6:26 ` Masahiro Yamada 0 siblings, 1 reply; 12+ messages in thread From: Andy Lutomirski @ 2016-03-14 4:44 UTC (permalink / raw) To: Masahiro Yamada Cc: Fenghua Yu, Thomas Gleixner, Ingo Molnar, Russell King, Michal Marek, linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, Nathan Lynch, Tony Luck, linux-ia64@vger.kernel.org, linux-arm-kernel@lists.infradead.org, H. Peter Anvin, X86 ML On Sun, Mar 13, 2016 at 9:36 PM, Masahiro Yamada <yamada.masahiro@socionext.com> wrote: > 2016-03-14 13:28 GMT+09:00 Andy Lutomirski <luto@amacapital.net>: >> On Sun, Mar 13, 2016 at 9:08 PM, Masahiro Yamada >> <yamada.masahiro@socionext.com> wrote: >>> >>> Hi Andy >>> >>> 2016-03-14 9:39 GMT+09:00 Andy Lutomirski <luto@amacapital.net>: >>> > On Mar 12, 2016 4:14 PM, "Masahiro Yamada" >>> > <yamada.masahiro@socionext.com> wrote: >>> >> >>> >> These targets are marked as PHONY. No need to add FORCE to their >>> >> dependency. >>> > >>> > If this is, in fact, correct, can you update >>> > Documentation/kbuild/makefiles.txt as well? >>> >>> Which line do you want me to update? >>> >> >> All the references to FORCE should probably mention .PHONY as an alternative. > > I do not get your point. > > All the examples in the makefile.txt correctly reference to FORCE. > They are not PHONY targets. > No need to update. But they could be. For example: $(obj)/image: vmlinux FORCE $(call if_changed,objcopy) could be: .PHONY: $(obj)/image $(obj)/image: vmlinux $(call if_changed,objcopy) I would at least change: Note: It is a typical mistake to forget the FORCE prerequisite. to: Note: if-changed is only useful if make executes it, which won't happen if it determines that the inputs have not changed since the output was built. This can be avoided by specifying FORCE as a prerequisite or by making declaring the output as .PHONY. --Andy > > > > > -- > Best Regards > Masahiro Yamada -- Andy Lutomirski AMA Capital Management, LLC ^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] kbuild: drop FORCE from PHONY targets 2016-03-14 4:44 ` Andy Lutomirski @ 2016-03-14 6:26 ` Masahiro Yamada 2016-03-15 18:27 ` Andy Lutomirski 0 siblings, 1 reply; 12+ messages in thread From: Masahiro Yamada @ 2016-03-14 6:26 UTC (permalink / raw) To: Andy Lutomirski Cc: Fenghua Yu, Thomas Gleixner, Ingo Molnar, Russell King, Michal Marek, linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, Nathan Lynch, Tony Luck, linux-ia64@vger.kernel.org, linux-arm-kernel@lists.infradead.org, H. Peter Anvin, X86 ML Hi Andy, 2016-03-14 13:44 GMT+09:00 Andy Lutomirski <luto@amacapital.net>: > On Sun, Mar 13, 2016 at 9:36 PM, Masahiro Yamada > <yamada.masahiro@socionext.com> wrote: >> 2016-03-14 13:28 GMT+09:00 Andy Lutomirski <luto@amacapital.net>: >>> On Sun, Mar 13, 2016 at 9:08 PM, Masahiro Yamada >>> <yamada.masahiro@socionext.com> wrote: >>>> >>>> Hi Andy >>>> >>>> 2016-03-14 9:39 GMT+09:00 Andy Lutomirski <luto@amacapital.net>: >>>> > On Mar 12, 2016 4:14 PM, "Masahiro Yamada" >>>> > <yamada.masahiro@socionext.com> wrote: >>>> >> >>>> >> These targets are marked as PHONY. No need to add FORCE to their >>>> >> dependency. >>>> > >>>> > If this is, in fact, correct, can you update >>>> > Documentation/kbuild/makefiles.txt as well? >>>> >>>> Which line do you want me to update? >>>> >>> >>> All the references to FORCE should probably mention .PHONY as an alternative. >> >> I do not get your point. >> >> All the examples in the makefile.txt correctly reference to FORCE. >> They are not PHONY targets. >> No need to update. > > But they could be. For example: > > $(obj)/image: vmlinux FORCE > $(call if_changed,objcopy) > > could be: > > .PHONY: $(obj)/image > $(obj)/image: vmlinux > $(call if_changed,objcopy) > > I would at least change: > > Note: It is a typical mistake to forget the FORCE prerequisite. > > to: > > Note: if-changed is only useful if make executes it, which won't > happen if it determines that the inputs have not changed since the > output was built. This can be avoided by specifying FORCE as a > prerequisite or by making declaring the output as .PHONY. > No. This is absolutely wrong. PHONY and FORCE are not interchangeable. They have different behavior. I will show you how they behave differently. BTW, Linux 4.5 is out now. Let's try a simple experiment on it. The following shows that my source tree is v4.5 yamada@beagle:~/workspace/linux$ git describe v4.5 Example 1) Add the following code to the top Makefile. Please note "FORCE" is used here. yamada@beagle:~/workspace/linux$ git diff diff --git a/Makefile b/Makefile index 7b3ecdc..89b7d0d 100644 --- a/Makefile +++ b/Makefile @@ -914,6 +914,22 @@ export KBUILD_ALLDIRS := $(sort $(filter-out arch/%,$(vmlinux- vmlinux-deps := $(KBUILD_LDS) $(KBUILD_VMLINUX_INIT) $(KBUILD_VMLINUX_MAIN) +quiet_cmd_gen_foo = FOO $@ + cmd_gen_foo = (cat $<; echo hello) > $@ + +foo: bar FORCE + $(call if_changed,gen_foo) + +quiet_cmd_gen_bar = BAR $@ + cmd_gen_bar = (cat $<; echo $(GREETING)) > $@ + +bar: baz FORCE + $(call if_changed,gen_bar) + +baz: + @touch $@ + + # Final link of vmlinux cmd_link-vmlinux = $(CONFIG_SHELL) $< $(LD) $(LDFLAGS) $(LDFLAGS_vmlinux) quiet_cmd_link-vmlinux = LINK $@ Try the following. yamada@beagle:~/workspace/linux$ git clean -x -f yamada@beagle:~/workspace/linux$ make -s defconfig yamada@beagle:~/workspace/linux$ make GREETING=GoodMorning foo scripts/kconfig/conf --silentoldconfig Kconfig BAR bar FOO foo yamada@beagle:~/workspace/linux$ make GREETING=GoodMorning foo make: `foo' is up to date. yamada@beagle:~/workspace/linux$ make GREETING=GoodAfternoon foo BAR bar FOO foo yamada@beagle:~/workspace/linux$ make GREETING=GoodAfternoon foo make: `foo' is up to date. yamada@beagle:~/workspace/linux$ make GREETING=GoodEvening foo BAR bar FOO foo yamada@beagle:~/workspace/linux$ make GREETING=GoodEvening foo make: `foo' is up to date. Please notice "foo" and "bar" were not rebuilt when I gave the same command line as the previous run. When I changed the command line, "bar" was update and "foo" was also updated because "foo" depends on "bar". It means $(call if_changed,...) is working as expected. Example 2) Add the following to the top Makefile. Please notice that I just replaced "FORCE" with ".PHONY". diff --git a/Makefile b/Makefile index 7b3ecdc..a0899c3 100644 --- a/Makefile +++ b/Makefile @@ -914,6 +914,24 @@ export KBUILD_ALLDIRS := $(sort $(filter-out arch/%,$(vmlinux- vmlinux-deps := $(KBUILD_LDS) $(KBUILD_VMLINUX_INIT) $(KBUILD_VMLINUX_MAIN) +quiet_cmd_gen_foo = FOO $@ + cmd_gen_foo = (cat $<; echo hello) > $@ + +.PHONY: foo +foo: bar + $(call if_changed,gen_foo) + +quiet_cmd_gen_bar = BAR $@ + cmd_gen_bar = (cat $<; echo $(GREETING)) > $@ + +.PHONY: bar +bar: baz + $(call if_changed,gen_bar) + +baz: + @touch $@ + + # Final link of vmlinux cmd_link-vmlinux = $(CONFIG_SHELL) $< $(LD) $(LDFLAGS) $(LDFLAGS_vmlinux) quiet_cmd_link-vmlinux = LINK $@ Let's try the same thing. yamada@beagle:~/workspace/linux$ git clean -x -f yamada@beagle:~/workspace/linux$ make -s defconfig yamada@beagle:~/workspace/linux$ make GREETING=GoodMorning foo scripts/kconfig/conf --silentoldconfig Kconfig BAR bar FOO foo yamada@beagle:~/workspace/linux$ make GREETING=GoodMorning foo BAR bar FOO foo yamada@beagle:~/workspace/linux$ make GREETING=GoodMorning foo BAR bar FOO foo yamada@beagle:~/workspace/linux$ make GREETING=GoodAfternoon foo BAR bar FOO foo yamada@beagle:~/workspace/linux$ make GREETING=GoodAfternoon foo BAR bar FOO foo yamada@beagle:~/workspace/linux$ make GREETING=GoodAfternoon foo BAR bar FOO foo Did you notice the difference? The "foo" and "bar" are always rebuilt regardless the command line is changed or not. It means $(call if_changed,...) is not working. -- Best Regards Masahiro Yamada ^ permalink raw reply related [flat|nested] 12+ messages in thread
* Re: [PATCH] kbuild: drop FORCE from PHONY targets 2016-03-14 6:26 ` Masahiro Yamada @ 2016-03-15 18:27 ` Andy Lutomirski 2016-03-15 20:45 ` Michal Marek 0 siblings, 1 reply; 12+ messages in thread From: Andy Lutomirski @ 2016-03-15 18:27 UTC (permalink / raw) To: Masahiro Yamada Cc: Fenghua Yu, Thomas Gleixner, Russell King, Ingo Molnar, Michal Marek, X86 ML, linux-arm-kernel@lists.infradead.org, Tony Luck, Nathan Lynch, linux-kbuild@vger.kernel.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, H. Peter Anvin On Mar 13, 2016 11:26 PM, "Masahiro Yamada" <yamada.masahiro@socionext.com> wrote: > > Hi Andy, > > > 2016-03-14 13:44 GMT+09:00 Andy Lutomirski <luto@amacapital.net>: > > On Sun, Mar 13, 2016 at 9:36 PM, Masahiro Yamada > > <yamada.masahiro@socionext.com> wrote: > >> 2016-03-14 13:28 GMT+09:00 Andy Lutomirski <luto@amacapital.net>: > >>> On Sun, Mar 13, 2016 at 9:08 PM, Masahiro Yamada > >>> <yamada.masahiro@socionext.com> wrote: > >>>> > >>>> Hi Andy > >>>> > >>>> 2016-03-14 9:39 GMT+09:00 Andy Lutomirski <luto@amacapital.net>: > >>>> > On Mar 12, 2016 4:14 PM, "Masahiro Yamada" > >>>> > <yamada.masahiro@socionext.com> wrote: > >>>> >> > >>>> >> These targets are marked as PHONY. No need to add FORCE to their > >>>> >> dependency. > >>>> > > >>>> > If this is, in fact, correct, can you update > >>>> > Documentation/kbuild/makefiles.txt as well? > >>>> > >>>> Which line do you want me to update? > >>>> > >>> > >>> All the references to FORCE should probably mention .PHONY as an alternative. > >> > >> I do not get your point. > >> > >> All the examples in the makefile.txt correctly reference to FORCE. > >> They are not PHONY targets. > >> No need to update. > > > > But they could be. For example: > > > > $(obj)/image: vmlinux FORCE > > $(call if_changed,objcopy) > > > > could be: > > > > .PHONY: $(obj)/image > > $(obj)/image: vmlinux > > $(call if_changed,objcopy) > > > > I would at least change: > > > > Note: It is a typical mistake to forget the FORCE prerequisite. > > > > to: > > > > Note: if-changed is only useful if make executes it, which won't > > happen if it determines that the inputs have not changed since the > > output was built. This can be avoided by specifying FORCE as a > > prerequisite or by making declaring the output as .PHONY. > > > > > No. This is absolutely wrong. > PHONY and FORCE are not interchangeable. > > They have different behavior. > I will show you how they behave differently. > > > BTW, Linux 4.5 is out now. > > Let's try a simple experiment on it. > > > The following shows that my source tree is v4.5 > > yamada@beagle:~/workspace/linux$ git describe > v4.5 > > > > Example 1) > > > Add the following code to the top Makefile. > > Please note "FORCE" is used here. > > > yamada@beagle:~/workspace/linux$ git diff > diff --git a/Makefile b/Makefile > index 7b3ecdc..89b7d0d 100644 > --- a/Makefile > +++ b/Makefile > @@ -914,6 +914,22 @@ export KBUILD_ALLDIRS := $(sort $(filter-out > arch/%,$(vmlinux- > > vmlinux-deps := $(KBUILD_LDS) $(KBUILD_VMLINUX_INIT) $(KBUILD_VMLINUX_MAIN) > > +quiet_cmd_gen_foo = FOO $@ > + cmd_gen_foo = (cat $<; echo hello) > $@ > + > +foo: bar FORCE > + $(call if_changed,gen_foo) > + > +quiet_cmd_gen_bar = BAR $@ > + cmd_gen_bar = (cat $<; echo $(GREETING)) > $@ > + > +bar: baz FORCE > + $(call if_changed,gen_bar) > + > +baz: > + @touch $@ > + > + > # Final link of vmlinux > cmd_link-vmlinux = $(CONFIG_SHELL) $< $(LD) $(LDFLAGS) $(LDFLAGS_vmlinux) > quiet_cmd_link-vmlinux = LINK $@ > > > > Try the following. > > yamada@beagle:~/workspace/linux$ git clean -x -f > yamada@beagle:~/workspace/linux$ make -s defconfig > yamada@beagle:~/workspace/linux$ make GREETING=GoodMorning foo > scripts/kconfig/conf --silentoldconfig Kconfig > BAR bar > FOO foo > yamada@beagle:~/workspace/linux$ make GREETING=GoodMorning foo > make: `foo' is up to date. > yamada@beagle:~/workspace/linux$ make GREETING=GoodAfternoon foo > BAR bar > FOO foo > yamada@beagle:~/workspace/linux$ make GREETING=GoodAfternoon foo > make: `foo' is up to date. > yamada@beagle:~/workspace/linux$ make GREETING=GoodEvening foo > BAR bar > FOO foo > yamada@beagle:~/workspace/linux$ make GREETING=GoodEvening foo > make: `foo' is up to date. > > > > > Please notice "foo" and "bar" were not rebuilt > when I gave the same command line as the previous run. > > > When I changed the command line, "bar" was update > and "foo" was also updated because "foo" depends on "bar". > > > It means $(call if_changed,...) is working as expected. > > > > > > > Example 2) > > > Add the following to the top Makefile. > Please notice that I just replaced "FORCE" with ".PHONY". > > > > diff --git a/Makefile b/Makefile > index 7b3ecdc..a0899c3 100644 > --- a/Makefile > +++ b/Makefile > @@ -914,6 +914,24 @@ export KBUILD_ALLDIRS := $(sort $(filter-out > arch/%,$(vmlinux- > > vmlinux-deps := $(KBUILD_LDS) $(KBUILD_VMLINUX_INIT) $(KBUILD_VMLINUX_MAIN) > > +quiet_cmd_gen_foo = FOO $@ > + cmd_gen_foo = (cat $<; echo hello) > $@ > + > +.PHONY: foo > +foo: bar > + $(call if_changed,gen_foo) > + > +quiet_cmd_gen_bar = BAR $@ > + cmd_gen_bar = (cat $<; echo $(GREETING)) > $@ > + > +.PHONY: bar > +bar: baz > + $(call if_changed,gen_bar) > + > +baz: > + @touch $@ > + > + > # Final link of vmlinux > cmd_link-vmlinux = $(CONFIG_SHELL) $< $(LD) $(LDFLAGS) $(LDFLAGS_vmlinux) > quiet_cmd_link-vmlinux = LINK $@ > > > > Let's try the same thing. > > > > yamada@beagle:~/workspace/linux$ git clean -x -f > yamada@beagle:~/workspace/linux$ make -s defconfig > yamada@beagle:~/workspace/linux$ make GREETING=GoodMorning foo > scripts/kconfig/conf --silentoldconfig Kconfig > BAR bar > FOO foo > yamada@beagle:~/workspace/linux$ make GREETING=GoodMorning foo > BAR bar > FOO foo > yamada@beagle:~/workspace/linux$ make GREETING=GoodMorning foo > BAR bar > FOO foo > yamada@beagle:~/workspace/linux$ make GREETING=GoodAfternoon foo > BAR bar > FOO foo > yamada@beagle:~/workspace/linux$ make GREETING=GoodAfternoon foo > BAR bar > FOO foo > yamada@beagle:~/workspace/linux$ make GREETING=GoodAfternoon foo > BAR bar > FOO foo > > > Did you notice the difference? > > The "foo" and "bar" are always rebuilt > regardless the command line is changed or not. > > It means $(call if_changed,...) is not working. > Fair enough, although I'm curious why this happens. It might be worth changing the docs to say that .PHONY is *not* an substitute for FORCE in that context, then. --Andy ^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] kbuild: drop FORCE from PHONY targets 2016-03-15 18:27 ` Andy Lutomirski @ 2016-03-15 20:45 ` Michal Marek 2016-03-15 20:48 ` Andy Lutomirski 0 siblings, 1 reply; 12+ messages in thread From: Michal Marek @ 2016-03-15 20:45 UTC (permalink / raw) To: Andy Lutomirski Cc: Masahiro Yamada, Fenghua Yu, Thomas Gleixner, Russell King, Ingo Molnar, X86 ML, linux-arm-kernel@lists.infradead.org, Tony Luck, Nathan Lynch, linux-kbuild@vger.kernel.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, H. Peter Anvin Dne 15.3.2016 v 19:27 Andy Lutomirski napsal(a): > Fair enough, although I'm curious why this happens. It might be worth > changing the docs to say that .PHONY is *not* an substitute for FORCE > in that context, then. These two are unrelated, except that FORCE is redundant for a .PHONY target. FORCE is our idiom to tell make to always remake the target and let us handle the dependencies manually. Listing a target as .PHONY tells make that the target will not produce a file of the same name (typically, "all", "install", etc). Michal ^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] kbuild: drop FORCE from PHONY targets 2016-03-15 20:45 ` Michal Marek @ 2016-03-15 20:48 ` Andy Lutomirski 2016-03-17 3:52 ` Masahiro Yamada 0 siblings, 1 reply; 12+ messages in thread From: Andy Lutomirski @ 2016-03-15 20:48 UTC (permalink / raw) To: Michal Marek Cc: Masahiro Yamada, Fenghua Yu, Thomas Gleixner, Russell King, Ingo Molnar, X86 ML, linux-arm-kernel@lists.infradead.org, Tony Luck, Nathan Lynch, linux-kbuild@vger.kernel.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, H. Peter Anvin On Tue, Mar 15, 2016 at 1:45 PM, Michal Marek <mmarek@suse.com> wrote: > Dne 15.3.2016 v 19:27 Andy Lutomirski napsal(a): >> Fair enough, although I'm curious why this happens. It might be worth >> changing the docs to say that .PHONY is *not* an substitute for FORCE >> in that context, then. > > These two are unrelated, except that FORCE is redundant for a .PHONY > target. FORCE is our idiom to tell make to always remake the target and > let us handle the dependencies manually. Listing a target as .PHONY > tells make that the target will not produce a file of the same name > (typically, "all", "install", etc). > Except that apparently if-changed doesn't work on .PHONY targets that don't specify FORCE, which confuses me. --Andy -- Andy Lutomirski AMA Capital Management, LLC ^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] kbuild: drop FORCE from PHONY targets 2016-03-15 20:48 ` Andy Lutomirski @ 2016-03-17 3:52 ` Masahiro Yamada 0 siblings, 0 replies; 12+ messages in thread From: Masahiro Yamada @ 2016-03-17 3:52 UTC (permalink / raw) To: Andy Lutomirski Cc: Michal Marek, Fenghua Yu, Thomas Gleixner, Russell King, Ingo Molnar, X86 ML, linux-arm-kernel@lists.infradead.org, Tony Luck, Nathan Lynch, linux-kbuild@vger.kernel.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, H. Peter Anvin Hi Andy, 2016-03-16 5:48 GMT+09:00 Andy Lutomirski <luto@amacapital.net>: > On Tue, Mar 15, 2016 at 1:45 PM, Michal Marek <mmarek@suse.com> wrote: >> Dne 15.3.2016 v 19:27 Andy Lutomirski napsal(a): >>> Fair enough, although I'm curious why this happens. It might be worth >>> changing the docs to say that .PHONY is *not* an substitute for FORCE >>> in that context, then. >> >> These two are unrelated, except that FORCE is redundant for a .PHONY >> target. FORCE is our idiom to tell make to always remake the target and >> let us handle the dependencies manually. Listing a target as .PHONY >> tells make that the target will not produce a file of the same name >> (typically, "all", "install", etc). >> > > Except that apparently if-changed doesn't work on .PHONY targets that > don't specify FORCE, which confuses me. OK, I will try to explain it. I hope this will help you, not confuse you even more... I think the difference of Kbuild behavior comes down to "$?" behavior of GNU Make. Please see the definition of "if_changed". if_changed = $(if $(strip $(any-prereq) $(arg-check)), \ @set -e; \ $(echo-cmd) $(cmd_$(1)); \ printf '%s\n' 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd) The "if_changed" does some actions if "any-prereq" or "arg-check" is non-empty. Next, let's take a look at the definition of "any-prereq" any-prereq = $(filter-out $(PHONY),$?) $(filter-out $(PHONY) $(wildcard $^),$^) It seems $? makes the difference between FORCE and PHONY. The GNU Make manual says as follows: -------------------->8----------------------------------- $? The names of all prerequisites that are newer than the target, separated by spaces. --------------------8<----------------------------------- >From this statement, it is unclear what happens to $? if the target is a PHONY target. I am not a GNU Make developer, so I have no idea about the detailed implementation, but anyway let's try simple experiments. [Example 3] Let's write a simple Makefile as follows. --------------------->8--------------------- foo: bar FORCE echo $$? is "$?" cp $< $@ bar: touch $@ .PHONY: FORCE FORCE: ----------------------8<-------------------- yamada@beagle:~/workspace/test$ rm -f foo bar yamada@beagle:~/workspace/test$ make touch bar echo $? is "bar FORCE" 0 is bar FORCE cp bar foo yamada@beagle:~/workspace/test$ make echo $? is "" 0 is cp bar foo yamada@beagle:~/workspace/test$ make echo $? is "" 0 is cp bar foo As we expected, $? contains the prerequisite "bar", but it is empty for the second run or later (because "foo" is newer than "bar"). [Example 4] Let's replace the FORCE with PHONY. --------------------->8--------------------- .PHONY: foo foo: bar echo $$? is "$?" cp $< $@ bar: touch $@ ----------------------8<-------------------- yamada@beagle:~/workspace/test2$ rm -f foo bar yamada@beagle:~/workspace/test2$ make touch bar echo $? is "bar" 0 is bar cp bar foo yamada@beagle:~/workspace/test2$ make echo $? is "bar" 0 is bar cp bar foo yamada@beagle:~/workspace/test2$ make echo $? is "bar" 0 is bar cp bar foo This time, $? always contains "bar" nevertheless "foo" is newer than "bar" on the second run or later. So, it looks like GNU Make assumes that all the prerequisites of a PHONY target are always newer than the target. Go back to the definition of "any-prereq", any-prereq = $(filter-out $(PHONY),$?) $(filter-out $(PHONY) $(wildcard $^),$^) If the prerequisite is not a PHONY target (like the "baz" in the example 2 in my former email), it is not filtered out from $?. So, any-prereq is non-empty and if_changed updates the target. -- Best Regards Masahiro Yamada ^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] kbuild: drop FORCE from PHONY targets 2016-03-13 0:13 [PATCH] kbuild: drop FORCE from PHONY targets Masahiro Yamada 2016-03-14 0:39 ` Andy Lutomirski @ 2016-04-20 8:29 ` Michal Marek 1 sibling, 0 replies; 12+ messages in thread From: Michal Marek @ 2016-04-20 8:29 UTC (permalink / raw) To: Masahiro Yamada, linux-kbuild Cc: Tony Luck, Nathan Lynch, linux-ia64, x86, H. Peter Anvin, linux-kernel, Thomas Gleixner, Russell King, Andy Lutomirski, Ingo Molnar, Fenghua Yu, linux-arm-kernel Dne 13.3.2016 v 01:13 Masahiro Yamada napsal(a): > These targets are marked as PHONY. No need to add FORCE to their > dependency. > > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> > --- > > Makefile | 8 ++++---- > arch/arm/vdso/Makefile | 2 +- > arch/ia64/Makefile | 4 ++-- > arch/x86/entry/vdso/Makefile | 4 ++-- > 4 files changed, 9 insertions(+), 9 deletions(-) Applied to kbuild.git#kbuild now, sorry for the delay. Michal ^ permalink raw reply [flat|nested] 12+ messages in thread
end of thread, other threads:[~2016-04-20 8:29 UTC | newest] Thread overview: 12+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2016-03-13 0:13 [PATCH] kbuild: drop FORCE from PHONY targets Masahiro Yamada 2016-03-14 0:39 ` Andy Lutomirski 2016-03-14 4:08 ` Masahiro Yamada 2016-03-14 4:28 ` Andy Lutomirski 2016-03-14 4:36 ` Masahiro Yamada 2016-03-14 4:44 ` Andy Lutomirski 2016-03-14 6:26 ` Masahiro Yamada 2016-03-15 18:27 ` Andy Lutomirski 2016-03-15 20:45 ` Michal Marek 2016-03-15 20:48 ` Andy Lutomirski 2016-03-17 3:52 ` Masahiro Yamada 2016-04-20 8:29 ` Michal Marek
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