[PATCH 04/10] ARM: pass -marm to gcc by default

On Friday 10 August 2012, Dave Martin wrote:

On Thu, Aug 09, 2012 at 05:22:30PM -0400, Nicolas Pitre wrote:

quoted

On Thu, 9 Aug 2012, Russell King - ARM Linux wrote:

quoted

On Thu, Aug 09, 2012 at 05:12:58PM -0400, Nicolas Pitre wrote:

quoted

CFLAGS_THUMB2 should probably be renamed to something more appropriate 
in this case, e.g. CFLAGS_MODE.

CFLAGS_ISA would be more relevant to it, because it's selecting the
instruction set.

Agreed.  This particular TLA escaped my mind somehow.

Seems fair enough.  It doesn't quite match the official architectural
terminology, but it clear enough what it means, and less cumbersome than
the alternatives.

Best not to use MODE though.  That word is way too overloaded.

Ok. I already noticed that we already set -marm in KBUILD_CFLAGS but
not in the AFLAGS. This new version should cover all the issues
and make it more obvious what's actually going on.

	Arnd

8<----

From 34763772164d1442509f27d7f8a09326ff4b7878 Mon Sep 17 00:00:00 2001

From: Arnd Bergmann <arnd@arndb.de>
Date: Mon, 30 Apr 2012 12:40:00 +0000
Subject: [PATCH] ARM: pass -marm to gcc by default for both C and assembler

The Linaro cross toolchain and probably others nowadays default to
building in THUMB2 mode. When building a kernel for a CPU that does
not support THUMB2, the compiler complains about incorrect flags.
We can work around this by setting -marm for all non-T2 builds.

Without this patch, building assabet_defconfig results in:

usr/initramfs_data.S:1:0: warning: target CPU does not support THUMB instructions [enabled by default]
arch/arm/nwfpe/entry.S:1:0: warning: target CPU does not support THUMB instructions [enabled by default]
firmware/cis/PCMLM28.cis.gen.S:1:0: warning: target CPU does not support THUMB instructions [enabled by default]
(and many more)

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Russell King <redacted>
Cc: Dave Martin <redacted>

diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index 30eae87..ca0dabc 100644
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile

@@ -21,8 +21,6 @@ endif
 OBJCOPYFLAGS	:=-O binary -R .comment -S
 GZFLAGS		:=-9
 #KBUILD_CFLAGS	+=-pipe
-# Explicitly specifiy 32-bit ARM ISA since toolchain default can be -mthumb:
-KBUILD_CFLAGS	+=$(call cc-option,-marm,)
 
 # Never generate .eh_frame
 KBUILD_CFLAGS	+= $(call cc-option,-fno-dwarf2-cfi-asm)

@@ -105,17 +103,20 @@ endif
 ifeq ($(CONFIG_THUMB2_KERNEL),y)
 AFLAGS_AUTOIT	:=$(call as-option,-Wa$(comma)-mimplicit-it=always,-Wa$(comma)-mauto-it)
 AFLAGS_NOWARN	:=$(call as-option,-Wa$(comma)-mno-warn-deprecated,-Wa$(comma)-W)
-CFLAGS_THUMB2	:=-mthumb $(AFLAGS_AUTOIT) $(AFLAGS_NOWARN)
-AFLAGS_THUMB2	:=$(CFLAGS_THUMB2) -Wa$(comma)-mthumb
+CFLAGS_ISA	:=-mthumb $(AFLAGS_AUTOIT) $(AFLAGS_NOWARN)
+AFLAGS_ISA	:=$(CFLAGS_ISA) -Wa$(comma)-mthumb
 # Work around buggy relocation from gas if requested:
 ifeq ($(CONFIG_THUMB2_AVOID_R_ARM_THM_JUMP11),y)
 CFLAGS_MODULE	+=-fno-optimize-sibling-calls
 endif
+else
+CFLAGS_ISA	:=$(call cc-option,-marm,)
+AFLAGS_ISA	:=$(CFLAGS_ISA)
 endif
 
 # Need -Uarm for gcc < 3.x
-KBUILD_CFLAGS	+=$(CFLAGS_ABI) $(CFLAGS_THUMB2) $(arch-y) $(tune-y) $(call cc-option,-mshort-load-bytes,$(call cc-option,-malignment-traps,)) -msoft-float -Uarm
-KBUILD_AFLAGS	+=$(CFLAGS_ABI) $(AFLAGS_THUMB2) $(arch-y) $(tune-y) -include asm/unified.h -msoft-float
+KBUILD_CFLAGS	+=$(CFLAGS_ABI) $(CFLAGS_ISA) $(arch-y) $(tune-y) $(call cc-option,-mshort-load-bytes,$(call cc-option,-malignment-traps,)) -msoft-float -Uarm
+KBUILD_AFLAGS	+=$(CFLAGS_ABI) $(AFLAGS_ISA) $(arch-y) $(tune-y) -include asm/unified.h -msoft-float
 
 CHECKFLAGS	+= -D__arm__