From: Arnaud Lacombe <lacombar@gmail.com> To: Nicolas Pitre <nico@fluxnic.net> Cc: linux-kbuild@vger.kernel.org, linux-arm-kernel@lists.infradead.org, lkml <linux-kernel@vger.kernel.org> Subject: Re: [RFC] Kbuild: allow code re-use across different directories Date: Wed, 7 Sep 2011 15:34:35 -0400 [thread overview] Message-ID: <CACqU3MVF8XSdKi0PeZF5SFaH9i2HPqCjkMqccyb83x4V_1Vs1g@mail.gmail.com> (raw) In-Reply-To: <alpine.LFD.2.00.1109071437400.20358@xanadu.home> Hi, On Wed, Sep 7, 2011 at 3:07 PM, Nicolas Pitre <nico@fluxnic.net> wrote: > On Fri, 19 Aug 2011, Arnaud Lacombe wrote: > >> Hi folks, >> >> The attached patch modify Kbuild to allow to directly re-use code in multiple >> directory without having to go through a copy. Technically, it changes Kbuild to >> use by default the VPATH feature of GNU make and provides accessors for Makefile >> to change it indirectly. >> >> Considering: >> >> arch/foo/lib: >> fancy.c >> >> We want to be able to build it with -DPANTS=32 in the kernel, but the >> bootloader requires -DPANTS_SIZE=30. >> >> Currently we would do, either: >> >> arch/foo/lib/Makefile >> LDFLAGS_fancy.o := -DPANTS=32 >> obj-y += fancy.o >> >> and, either: >> >> arch/foo/boot/Makefile: >> LDFLAGS_fancy.o := -DPANTS=30 >> obj-y += fancy.o >> $(obj)/fancy.c: $(srctree)/arch/foo/lib/fancy.c >> $(call cmd,shipped) >> >> or >> >> arch/foo/boot/Makefile: >> LDFLAGS_fancy.o := -DPANTS=30 >> obj-y += fancy.o >> $(obj)/fancy.o: $(srctree)/arch/foo/lib/fancy.c >> $(call cmd,cc_c_o) >> >> The former implies an extra copy of the source file, the latter expose Kbuild >> internal function. >> >> With the attached patch, we would do: >> >> arch/foo/boot/Makefile: >> LDFLAGS_fancy.o := -DPANTS=30 >> obj-y += fancy.o >> vpath-y += $(srctree)/arch/foo/lib >> >> and let GNU make do the job. >> >> Comments welcome, > > It doesn't work. Whatever I do to arch/arm/boot/compressed/Makefile > (which admittedly looks a bit hairy and could benefit from a shave) in > order to remove the $(call cmd,shipped) used with lib1funcs.S, I always > end up with: > > make[2]: *** No rule to make target `arch/arm/boot/compressed/lib1funcs.S', needed by `arch/arm/boot/compressed/lib1funcs.o'. Stop. > What was the exact change you made which triggered this ? Thanks, - Arnaud > Obviously, restoring the explicit dependency with a $(call cmd,as_o_S) > does make it work, but this is rather against the point of your patch. > > Do you have an example of how arch/arm/boot/compressed/Makefile should > be changed to benefit from your patch? > > > Nicolas >
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From: lacombar@gmail.com (Arnaud Lacombe) To: linux-arm-kernel@lists.infradead.org Subject: [RFC] Kbuild: allow code re-use across different directories Date: Wed, 7 Sep 2011 15:34:35 -0400 [thread overview] Message-ID: <CACqU3MVF8XSdKi0PeZF5SFaH9i2HPqCjkMqccyb83x4V_1Vs1g@mail.gmail.com> (raw) In-Reply-To: <alpine.LFD.2.00.1109071437400.20358@xanadu.home> Hi, On Wed, Sep 7, 2011 at 3:07 PM, Nicolas Pitre <nico@fluxnic.net> wrote: > On Fri, 19 Aug 2011, Arnaud Lacombe wrote: > >> Hi folks, >> >> The attached patch modify Kbuild to allow to directly re-use code in multiple >> directory without having to go through a copy. Technically, it changes Kbuild to >> use by default the VPATH feature of GNU make and provides accessors for Makefile >> to change it indirectly. >> >> Considering: >> >> arch/foo/lib: >> fancy.c >> >> We want to be able to build it with -DPANTS=32 in the kernel, but the >> bootloader requires -DPANTS_SIZE=30. >> >> Currently we would do, either: >> >> arch/foo/lib/Makefile >> LDFLAGS_fancy.o := -DPANTS=32 >> obj-y += fancy.o >> >> and, either: >> >> arch/foo/boot/Makefile: >> LDFLAGS_fancy.o := -DPANTS=30 >> obj-y += fancy.o >> $(obj)/fancy.c: $(srctree)/arch/foo/lib/fancy.c >> ? ? ? $(call cmd,shipped) >> >> or >> >> arch/foo/boot/Makefile: >> LDFLAGS_fancy.o := -DPANTS=30 >> obj-y += fancy.o >> $(obj)/fancy.o: $(srctree)/arch/foo/lib/fancy.c >> ? ? ? $(call cmd,cc_c_o) >> >> The former implies an extra copy of the source file, the latter expose Kbuild >> internal function. >> >> With the attached patch, we would do: >> >> arch/foo/boot/Makefile: >> LDFLAGS_fancy.o := -DPANTS=30 >> obj-y += fancy.o >> vpath-y += $(srctree)/arch/foo/lib >> >> and let GNU make do the job. >> >> Comments welcome, > > It doesn't work. ?Whatever I do to arch/arm/boot/compressed/Makefile > (which admittedly looks a bit hairy and could benefit from a shave) in > order to remove the $(call cmd,shipped) used with lib1funcs.S, I always > end up with: > > make[2]: *** No rule to make target `arch/arm/boot/compressed/lib1funcs.S', needed by `arch/arm/boot/compressed/lib1funcs.o'. ?Stop. > What was the exact change you made which triggered this ? Thanks, - Arnaud > Obviously, restoring the explicit dependency with a $(call cmd,as_o_S) > does make it work, but this is rather against the point of your patch. > > Do you have an example of how arch/arm/boot/compressed/Makefile should > be changed to benefit from your patch? > > > Nicolas >
next prev parent reply other threads:[~2011-09-07 19:34 UTC|newest] Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top 2011-08-20 0:37 [RFC] Kbuild: allow code re-use across different directories Arnaud Lacombe 2011-08-20 0:37 ` Arnaud Lacombe 2011-08-22 8:42 ` Cong Wang 2011-08-22 8:42 ` Cong Wang 2011-08-30 0:31 ` Arnaud Lacombe 2011-08-30 0:31 ` Arnaud Lacombe 2011-08-30 4:32 ` Nicolas Pitre 2011-08-30 4:32 ` Nicolas Pitre 2011-08-30 4:36 ` Arnaud Lacombe 2011-08-30 4:36 ` Arnaud Lacombe 2011-09-07 19:07 ` Nicolas Pitre 2011-09-07 19:07 ` Nicolas Pitre 2011-09-07 19:34 ` Arnaud Lacombe [this message] 2011-09-07 19:34 ` Arnaud Lacombe 2011-09-07 19:59 ` Nicolas Pitre 2011-09-07 19:59 ` Nicolas Pitre 2011-09-07 20:52 ` Arnaud Lacombe 2011-09-07 20:52 ` Arnaud Lacombe 2011-09-08 4:50 ` Arnaud Lacombe 2011-09-08 4:50 ` Arnaud Lacombe 2011-09-08 20:33 ` Nicolas Pitre 2011-09-08 20:33 ` Nicolas Pitre 2011-09-09 1:22 ` Arnaud Lacombe 2011-09-09 1:22 ` Arnaud Lacombe 2011-09-09 12:32 ` Michal Marek 2011-09-09 12:32 ` Michal Marek 2011-09-09 16:16 ` Arnaud Lacombe 2011-09-09 16:16 ` Arnaud Lacombe 2011-09-08 18:24 ` Arnaud Lacombe 2011-09-09 12:30 ` Michal Marek 2011-09-09 12:30 ` Michal Marek 2011-09-13 21:13 ` Arnaud Lacombe 2011-09-13 21:13 ` Arnaud Lacombe 2011-09-14 1:48 ` Michal Marek 2011-09-14 1:48 ` Michal Marek
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