[PATCH] fix Makefile to ensure proper options get passed from gcc

[PATCH] fix Makefile to ensure proper options get passed from gcc

[Jory A. Pratt]

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if -D__KERNEL__ is not passed via KBUILD_CFLAGS the compiler can have 
options passed by default that will unset
other options such as -ffreestanding or -fno-toplevel-reorder if the 
compiler is passing -fPIE.

refer to fix-fpie-from-being-used.diff

Another option that was suggested from another user was to pass 
-D__KERNEL__ via Kbuild.include, patch is also attached.
either patch would work, There is no risk of breakage, benefit is for 
those who use a hardened toolchain.

fix-cc-options-check.patch

I believe we should pass the option via KBUILD_CFLAGS as to not confuse 
the fact that we are not building CPP code, but rather C code.

Also correct me if I am wrong but last I knew only part of kernel that 
was cpp was qconfig.

-Jory

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signed off by: Jory A. Pratt <anarchy@gentoo.org>

When -fPIE is pass to cc1 it can't use -ffreestanding or -fno-toplevel-reorder.
This will cause issues in video-vga.c when compiled leaving a user with no video
modes avaliable when booting system.
Many thanks to Vinky for tracking down bug.

--- Makefile~	2009-08-27 21:38:59.809945943 -0500
+++ Makefile	2009-08-27 21:40:04.204922755 -0500
@@ -348,7 +348,8 @@
 		   -fno-strict-aliasing -fno-common \
 		   -Werror-implicit-function-declaration \
 		   -Wno-format-security \
-		   -fno-delete-null-pointer-checks
+		   -fno-delete-null-pointer-checks \
+		   -D__KERNEL__
 KBUILD_AFLAGS   := -D__ASSEMBLY__
 
 # Read KERNELRELEASE from include/config/kernel.release (if it exists)

[-- Attachment #3: fix-cc-options-check.patch --]
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2009-08-28		Magnus Granberg		<zorry@ume.nu>
		
		#282201
		* scripts/Kbuild.incude		add $(KBUILD_CPPFLAGS)

--- scripts/Kbuild.include.zorry	2009-08-28 01:50:41.000000000 +0000
+++ scripts/Kbuild.include	2009-08-28 01:50:31.000000000 +0000
@@ -105,12 +105,12 @@
 # Usage: cflags-y += $(call cc-option,-march=winchip-c6,-march=i586)
 
 cc-option = $(call try-run,\
-	$(CC) $(KBUILD_CFLAGS) $(1) -c -xc /dev/null -o "$$TMP",$(1),$(2))
+	$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(1) -c -xc /dev/null -o "$$TMP",$(1),$(2))
 
 # cc-option-yn
 # Usage: flag := $(call cc-option-yn,-march=winchip-c6)
 cc-option-yn = $(call try-run,\
-	$(CC) $(KBUILD_CFLAGS) $(1) -c -xc /dev/null -o "$$TMP",y,n)
+	$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(1) -c -xc /dev/null -o "$$TMP",y,n)
 
 # cc-option-align
 # Prefix align with either -falign or -malign