ARM: enable Thumb build

Enable Thumb build and ARM-Thumb interworking based on the new config flag CONFIG_SYS_THUMB_BUILD Signed-off-by: Aneesh V <aneesh@ti.com> Acked-by: Mike Frysinger <vapier@gentoo.org>

ARM: enable Thumb build
Enable Thumb build and ARM-Thumb interworking based on the new config flag CONFIG_SYS_THUMB_BUILD Signed-off-by: Aneesh V <aneesh@ti.com> Acked-by: Mike Frysinger <vapier@gentoo.org>
Aneesh V · Albert ARIBAUD
1 parent 74236acacc
Showing 2 changed files with 23 additions and 7 deletions Side-by-side Diff
README
arch/arm/config.mk
@@ -432,6 +432,14 @@
 		Select high exception vectors of the ARM core, e.g., do not
 		clear the V bit of the c1 register of CP15.
  
+		CONFIG_SYS_THUMB_BUILD
+
+		Use this flag to build U-Boot using the Thumb instruction
+		set for ARM architectures. Thumb instruction set provides
+		better code density. For ARM architectures that support
+		Thumb2 this flag will result in Thumb2 code generated by
+		GCC.
+
 - Linux Kernel Interface:
 		CONFIG_CLOCKS_IN_MHZ
  
@@ -33,25 +33,33 @@
  
 PLATFORM_CPPFLAGS += -DCONFIG_ARM -D__ARM__
  
-# Explicitly specifiy 32-bit ARM ISA since toolchain default can be -mthumb:
-PF_CPPFLAGS_ARM := $(call cc-option,-marm,)
+# Choose between ARM/Thumb instruction sets
+ifeq ($(CONFIG_SYS_THUMB_BUILD),y)
+PF_CPPFLAGS_ARM := $(call cc-option, -mthumb -mthumb-interwork,\
+			$(call cc-option,-marm,)\
+			$(call cc-option,-mno-thumb-interwork,)\
+		)
+else
+PF_CPPFLAGS_ARM := $(call cc-option,-marm,) \
+		$(call cc-option,-mno-thumb-interwork,)
+endif
  
 # Try if EABI is supported, else fall back to old API,
 # i. e. for example:
 # - with ELDK 4.2 (EABI supported), use:
-#	-mabi=aapcs-linux -mno-thumb-interwork
+#	-mabi=aapcs-linux
 # - with ELDK 4.1 (gcc 4.x, no EABI), use:
-#	-mabi=apcs-gnu -mno-thumb-interwork
+#	-mabi=apcs-gnu
 # - with ELDK 3.1 (gcc 3.x), use:
-#	-mapcs-32 -mno-thumb-interwork
+#	-mapcs-32
 PF_CPPFLAGS_ABI := $(call cc-option,\
-			-mabi=aapcs-linux -mno-thumb-interwork,\
+			-mabi=aapcs-linux,\
 			$(call cc-option,\
 				-mapcs-32,\
 				$(call cc-option,\
 					-mabi=apcs-gnu,\
 				)\
-			) $(call cc-option,-mno-thumb-interwork,)\
+			)\
 		)
 PLATFORM_CPPFLAGS += $(PF_CPPFLAGS_ARM) $(PF_CPPFLAGS_ABI)
...	...	@@ -432,6 +432,14 @@
432	432	Select high exception vectors of the ARM core, e.g., do not
433	433	clear the V bit of the c1 register of CP15.
434	434
	435	+ CONFIG_SYS_THUMB_BUILD
	436	+
	437	+ Use this flag to build U-Boot using the Thumb instruction
	438	+ set for ARM architectures. Thumb instruction set provides
	439	+ better code density. For ARM architectures that support
	440	+ Thumb2 this flag will result in Thumb2 code generated by
	441	+ GCC.
	442	+
435	443	- Linux Kernel Interface:
436	444	CONFIG_CLOCKS_IN_MHZ
437	445
...	...	@@ -33,25 +33,33 @@
33	33
34	34	PLATFORM_CPPFLAGS += -DCONFIG_ARM -D__ARM__
35	35
36		-# Explicitly specifiy 32-bit ARM ISA since toolchain default can be -mthumb:
37		-PF_CPPFLAGS_ARM := $(call cc-option,-marm,)
	36	+# Choose between ARM/Thumb instruction sets
	37	+ifeq ($(CONFIG_SYS_THUMB_BUILD),y)
	38	+PF_CPPFLAGS_ARM := $(call cc-option, -mthumb -mthumb-interwork,\
	39	+ $(call cc-option,-marm,)\
	40	+ $(call cc-option,-mno-thumb-interwork,)\
	41	+ )
	42	+else
	43	+PF_CPPFLAGS_ARM := $(call cc-option,-marm,) \
	44	+ $(call cc-option,-mno-thumb-interwork,)
	45	+endif
38	46
39	47	# Try if EABI is supported, else fall back to old API,
40	48	# i. e. for example:
41	49	# - with ELDK 4.2 (EABI supported), use:
42		-# -mabi=aapcs-linux -mno-thumb-interwork
	50	+# -mabi=aapcs-linux
43	51	# - with ELDK 4.1 (gcc 4.x, no EABI), use:
44		-# -mabi=apcs-gnu -mno-thumb-interwork
	52	+# -mabi=apcs-gnu
45	53	# - with ELDK 3.1 (gcc 3.x), use:
46		-# -mapcs-32 -mno-thumb-interwork
	54	+# -mapcs-32
47	55	PF_CPPFLAGS_ABI := $(call cc-option,\
48		- -mabi=aapcs-linux -mno-thumb-interwork,\
	56	+ -mabi=aapcs-linux,\
49	57	$(call cc-option,\
50	58	-mapcs-32,\
51	59	$(call cc-option,\
52	60	-mabi=apcs-gnu,\
53	61	)\
54		- ) $(call cc-option,-mno-thumb-interwork,)\
	62	+ )\
55	63	)
56	64	PLATFORM_CPPFLAGS += $(PF_CPPFLAGS_ARM) $(PF_CPPFLAGS_ABI)
57	65