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    SubjectRe: [PATCH 1/3] Makefile: Include arch Makefiles as late as possible
    On Mon, Feb 16, 2009 at 05:20:01PM +0300, Anton Vorontsov wrote:
    > On Sat, Feb 14, 2009 at 08:57:02PM +0100, Sam Ravnborg wrote:
    > [...]
    > > > > --- a/Makefile
    > > > > +++ b/Makefile
    > > > > @@ -525,8 +525,6 @@ else
    > > > > KBUILD_CFLAGS += -O2
    > > > > endif
    > > > >
    > > > > -include $(srctree)/arch/$(SRCARCH)/Makefile
    > > > > -
    > > > > ifneq (CONFIG_FRAME_WARN,0)
    > > > > KBUILD_CFLAGS += $(call cc-option,-Wframe-larger-than=${CONFIG_FRAME_WARN})
    > > > > endif
    > > > > @@ -555,6 +553,8 @@ ifdef CONFIG_DEBUG_SECTION_MISMATCH
    > > > > KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions-called-once)
    > > > > endif
    > > > >
    > > > > +include $(srctree)/arch/$(SRCARCH)/Makefile
    > > > > +
    > > > > # arch Makefile may override CC so keep this after arch Makefile is included
    > > > > NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)
    > > > > CHECKFLAGS += $(NOSTDINC_FLAGS)
    > > > > --
    > > >
    > > > this patch is really for Sam to judge - Cc:-ed him.
    > >
    > > If we move the include further down then the following:
    > >
    > > # Force gcc to behave correct even for buggy distributions
    > > # Arch Makefiles may override this setting
    > > KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector)
    > >
    > > will most likely fail.
    >
    > Hm... I don't get it, the comment says that the arch "may override
    > this setting", but currently it may not, since arch makefile is
    > included before this line. So my patch also fixes this "bug", no?
    >
    > Or arches supposed to overwrite "cc-option" behaviour? Hm..
    >
    > There is an interesting commit:
    >
    > commit e06b8b98da071f7dd78fb7822991694288047df0
    > Author: Sam Ravnborg <sam@ravnborg.org>
    > Date: Wed Feb 13 22:43:28 2008 +0100
    >
    > kbuild: allow -fstack-protector to take effect
    > [...]
    > --- a/Makefile
    > +++ b/Makefile
    > @@ -507,6 +507,10 @@ else
    > KBUILD_CFLAGS += -O2
    > endif
    >
    > +# Force gcc to behave correct even for buggy distributions
    > +# Arch Makefiles may override this setting
    > +KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector)
    > +
    > include $(srctree)/arch/$(SRCARCH)/Makefile
    >
    > ifdef CONFIG_FRAME_POINTER
    > @@ -525,9 +529,6 @@ ifdef CONFIG_DEBUG_SECTION_MISMATCH
    > KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions-called-once)
    > endif
    >
    > -# Force gcc to behave correct even for buggy distributions
    > -KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector)
    > -
    > # arch Makefile may override CC so keep this after arch Makefile is included
    > NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)
    > CHECKFLAGS += $(NOSTDINC_FLAGS)
    >
    >
    > ^^ Which does the same (wrt fno-stack-protector) as the patch I
    > sent, i.e. includes arch Makefile later.
    >
    > But then, this commit reverted things back (w/o your Ack):
    >
    > commit bef5b54bd7bf8117c75cb943d64549134c6d9a1f
    > Author: Ralf Baechle <ralf@linux-mips.org>
    > Date: Wed Jul 16 13:02:24 2008 +0100
    >
    > Fix MIPS cross-compile problem
    > [...]
    > Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
    > Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

    Ok, I think I got it. It seems that Ralf was using this feature
    of arch/mips/Makefile:

    ifneq ($(SUBARCH),$(ARCH))
    ifeq ($(CROSS_COMPILE),)
    CROSS_COMPILE := $(call cc-cross-prefix, $(tool-archpref)-linux- $(tool-archpref)-linux-gnu- $(tool-archpref)-unknown-linux-gnu-)
    endif
    endif

    There are few arches that have "auto detection" of CROSS_COMPILE
    variable: mips, m68k, parisc, xtensa, h8300 and blackfin.

    So `normal' arches don't have any chance to overwrite the flags
    because of the few offenders above. ;-)

    > [...]
    > --- a/Makefile
    > +++ b/Makefile
    > @@ -508,6 +508,8 @@ else
    > KBUILD_CFLAGS += -O2
    > endif
    >
    > +include $(srctree)/arch/$(SRCARCH)/Makefile
    > +
    > ifneq (CONFIG_FRAME_WARN,0)
    > KBUILD_CFLAGS += $(call cc-option,-Wframe-larger-than=${CONFIG_FRAME_WARN})
    > endif
    > @@ -516,8 +518,6 @@ endif
    > # Arch Makefiles may override this setting
    > KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector)
    >
    > -include $(srctree)/arch/$(SRCARCH)/Makefile
    > -
    > ifdef CONFIG_FRAME_POINTER
    > KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls
    > else

    --
    Anton Vorontsov
    email: cbouatmailru@gmail.com
    irc://irc.freenode.net/bd2


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