Thumb-2: Add Thumb-2 support to the build files

This patch adds the necessary entries to the Makefile and Kconfig
files for building the Thumb-2 kernel.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

3 files changed, 22 insertions, 2 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index da28e7ba6083..a36b5a8b123e 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -983,6 +983,18 @@ config HZ
         default AT91_TIMER_HZ if ARCH_AT91
         default 100
 
+config THUMB2_KERNEL
+        bool "Compile the kernel in Thumb-2 mode"
+        depends on CPU_V7 && EXPERIMENTAL
+        select AEABI
+        select ARM_ASM_UNIFIED
+        help
+          By enabling this option, the kernel will be compiled in
+          Thumb-2 mode. A compiler/assembler that understand the unified
+          ARM-Thumb syntax is needed.
+
+          If unsure, say N.
+
 config ARM_ASM_UNIFIED
         bool
 
diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
index a89e4734b8f0..1a6f70e52921 100644
--- a/arch/arm/Kconfig.debug
+++ b/arch/arm/Kconfig.debug
@@ -8,6 +8,7 @@ source "lib/Kconfig.debug"
 # n, but then RMK will have to kill you ;).
 config FRAME_POINTER
         bool
+        depends on !THUMB2_KERNEL
         default y if !ARM_UNWIND
         help
           If you say N here, the resulting kernel will be slightly smaller and
diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index 3505572a21e6..e150f232458d 100644
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile
@@ -93,9 +93,16 @@ ifeq ($(CONFIG_ARM_UNWIND),y)
 CFLAGS_ABI      +=-funwind-tables
 endif
 
+ifeq ($(CONFIG_THUMB2_KERNEL),y)
+AFLAGS_AUTOIT   :=$(call as-option,-Wa$(comma)-mimplicit-it=thumb,-Wa$(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$(comma)-mthumb
+endif
+
 # Need -Uarm for gcc < 3.x
-KBUILD_CFLAGS   +=$(CFLAGS_ABI) $(arch-y) $(tune-y) $(call cc-option,-mshort-load-bytes,$(call cc-option,-malignment-traps,)) -msoft-float -Uarm
-KBUILD_AFLAGS   +=$(CFLAGS_ABI) $(arch-y) $(tune-y) -include asm/unified.h -msoft-float
+KBUILD_CFLAGS   +=$(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
 
 CHECKFLAGS      += -D__arm__