linux-kernel - Re: [PATCH 1/3] Makefile: Include arch Makefiles as late as possible

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Date:	Mon, 16 Feb 2009 17:20:01 +0300
From:	Anton Vorontsov <avorontsov@...mvista.com>
To:	Sam Ravnborg <sam@...nborg.org>
Cc:	Ingo Molnar <mingo@...e.hu>, Steven Rostedt <srostedt@...hat.com>,
	Paul Mackerras <paulus@...ba.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	linuxppc-dev@...abs.org, linux-kernel@...r.kernel.org,
	linux-rt-users@...r.kernel.org
Subject: Re: [PATCH 1/3] Makefile: Include arch Makefiles as late as
	possible

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@...nborg.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@...ux-mips.org>
Date:   Wed Jul 16 13:02:24 2008 +0100

    Fix MIPS cross-compile problem
    [...]
    Signed-off-by: Ralf Baechle <ralf@...ux-mips.org>
    Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>

[...]
--- 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@...il.com
irc://irc.freenode.net/bd2
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