Buildroot now builds armv6-m toolchain; NuTiny configuration now uses buildroot toolchain

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@5665 42af7a65-404d-4744-a932-0658087f49c3

7 files changed, 226 insertions, 86 deletions

diff --git a/misc/buildroot/ChangeLog b/misc/buildroot/ChangeLog
index 0053b1e92..e6ad07646 100644
--- a/misc/buildroot/ChangeLog
+++ b/misc/buildroot/ChangeLog
@@ -131,3 +131,5 @@ buildroot-1.12 2011-xx-xx <gnutt@nuttx.org>
 
 	* Fix typo toolchain/gdb/Config.in that prevented GDB 7.4 from building
 	  (from Ken Bannister).
+	* Add support for a Cortex-M0 toolchain based on GCC 4.6.3.
+
diff --git a/misc/buildroot/Config.in b/misc/buildroot/Config.in
index fe33b158d..21444f056 100644
--- a/misc/buildroot/Config.in
+++ b/misc/buildroot/Config.in
@@ -92,7 +92,9 @@ config BR2_arm926t
 config BR2_arm1136jf_s
 	bool "ARM1136JF-S"
 config BR2_cortex_m3
-	bool "Cortex-M3"
+	bool "Cortex-M3/M4"
+config BR2_cortex_m0
+	bool "Cortex-M0"
 config BR2_sa110
 	bool "SA110"
 config BR2_sa1100
@@ -217,6 +219,7 @@ config BR2_GCC_TARGET_TUNE
 	default arm9tdmi	if BR2_arm926t
 	default arm1136jf-s	if BR2_arm1136jf_s
 	default cortex-m3	if BR2_cortex_m3
+	default cortex-m0	if BR2_cortex_m0
 	default strongarm110	if BR2_sa110
 	default strongarm1100	if BR2_sa1100
 	default xscale		if BR2_xscale
@@ -235,6 +238,7 @@ config BR2_GCC_TARGET_ARCH
 	default armv5te		if BR2_arm926t || BR2_arm10t || BR2_xscale
 	default armv6j		if BR2_arm1136jf_s
 	default armv7-m		if BR2_cortex_m3
+	default armv6-m		if BR2_cortex_m0
 	default iwmmxt		if BR2_iwmmxt
 
 config BR2_GCC_TARGET_ABI
diff --git a/misc/buildroot/configs/README.txt b/misc/buildroot/configs/README.txt
index 6b76ff80d..0e9c6df5e 100644
--- a/misc/buildroot/configs/README.txt
+++ b/misc/buildroot/configs/README.txt
@@ -14,117 +14,124 @@ AVAILABLE CONFIGURATIONS
 ^^^^^^^^^^^^^^^^^^^^^^^^
 
 arm-defconfig
-	Builds an OABI ARM toolchain using gcc 3.4.6
+  Builds an OABI ARM toolchain using gcc 3.4.6
 
 arm7tdmi-defconfig-4.2.4
 arm920t-defconfig-4.2.4
 arm926t-defconfig-4.2.4
-	Builds an OABI ARM toolchain using gcc 4.2.4.  This configuration
-	builds both gcc and g++.  There are three versions: one for 
-	arm7tdmi (armv4t), arm920t (armv4t) and arm926t (arv5t) because
-	of differences in the way that soft floating is handled in between
-	the armv4t and arm5t architectures.
+  Builds an OABI ARM toolchain using gcc 4.2.4.  This configuration
+  builds both gcc and g++.  There are three versions: one for 
+  arm7tdmi (armv4t), arm920t (armv4t) and arm926t (arv5t) because
+  of differences in the way that soft floating is handled in between
+  the armv4t and arm5t architectures.
 
-	NOTE: The newer versions of GCC generate new sections and can
-	cause some problems for NuttX configurations developed under older
-	toolchains.  In particular, arm-elf-objcopy may fail with strange
-	errors.  If this occurs, try adding the following arguments to the
-	arm-elf-objcopy command "-R .note -R .note.gnu.build-id -R .comment"
+  NOTE: The newer versions of GCC generate new sections and can
+  cause some problems for NuttX configurations developed under older
+  toolchains.  In particular, arm-elf-objcopy may fail with strange
+  errors.  If this occurs, try adding the following arguments to the
+  arm-elf-objcopy command "-R .note -R .note.gnu.build-id -R .comment"
 
-	This logic is several configuration Make.defs files:
+  This logic is several configuration Make.defs files:
 
-	HOSTOS			=  ${shell uname -o}
+  HOSTOS =  ${shell uname -o}
 
-	ARCHCCVERSION		= ${shell $(CC) -v 2>&1 | sed -n '/^gcc version/p' | sed -e 's/^gcc version \([0-9\.]\)/\1/g' -e 's/[-\ ].*//g' -e '1q'}
-	ARCHCCMAJOR		= ${shell echo $(ARCHCCVERSION) | cut -d'.' -f1}
+  ARCHCCVERSION = ${shell $(CC) -v 2>&1 | sed -n '/^gcc version/p' | sed -e 's/^gcc version \([0-9\.]\)/\1/g' -e 's/[-\ ].*//g' -e '1q'}
+  ARCHCCMAJOR= ${shell echo $(ARCHCCVERSION) | cut -d'.' -f1}
 
-	ifeq ($(ARCHCCMAJOR),4)
-	ifneq ($(HOSTOS),Cygwin)
-	OBJCOPYARGS		= -R .note -R .note.gnu.build-id -R .comment
-	endif
-	endif
+  ifeq ($(ARCHCCMAJOR),4)
+  ifneq ($(HOSTOS),Cygwin)
+  OBJCOPYARGS = -R .note -R .note.gnu.build-id -R .comment
+  endif
+  endif
 
-	This change probably applies to other architectures as well (?)
+  This change probably applies to other architectures as well (?)
 
 arm920t-defconfig-4.3.3
 arm7tdmi-defconfig-4.3.3
-	Builds an OABI ARM toolchain using gcc 4.3.3.  These configurations
-	builds both gcc and g++ for the arm7tdmi (armv4t) or the arm920t
-	(armv4t).  These are udates to *-defconfig-4.2.4 (see notes above).
+  Builds an OABI ARM toolchain using gcc 4.3.3.  These configurations
+  builds both gcc and g++ for the arm7tdmi (armv4t) or the arm920t
+  (armv4t).  These are udates to *-defconfig-4.2.4 (see notes above).
+
+arm926t-defconfig-nxflat
+  This configuration build an NXFLAT toolchain (only) for
+  use with the ARM9.
 
 avr-defconfig-4.3.3
 avr-defconfig-5.4.2
-	Builds an AVR toolchain using gcc 4.3.3 or 4.5.2.  This configuration
-	builds both gcc and g++ for the AVR (armv4t). This toolchain
-	is intended to support the NuttX ATmega128 port.
+  Builds an AVR toolchain using gcc 4.3.3 or 4.5.2.  This configuration
+  builds both gcc and g++ for the AVR (armv4t). This toolchain
+  is intended to support the NuttX ATmega128 port.
+
+cortexm0-eabi-defconfig-4.6.3
+  Builds an EABI ARM toolchain for the Cortex-M0 using gcc 4.6.3.
+  This configuration builds gcc and g++ (NXFLAT is not currently
+  supported for the Cortex-M0).
 
 cortexm3-defconfig-4.3.3
-	Builds an OABI ARM toolchain for the Cortex-M3 using gcc 4.3.3.
-	This configuration builds gcc, g++ and the NXFLAT toolchain.
+  Builds an OABI ARM toolchain for the Cortex-M3 using gcc 4.3.3.
+  This configuration builds gcc, g++ and the NXFLAT toolchain.
+
+cortexm3-eabi-defconfig-4.5.2
+  Builds an EABI ARM toolchain for the Cortex-M3 using gcc 4.5.2.
+  This configuration builds gcc, g++ and the NXFLAT toolchain.
 
 cortexm3-eabi-defconfig-4.6.3
-        Builds an EABI ARM toolchain for the Cortex-M3 using gcc 4.6.3.
-        This configuration builds gcc, g++ and the NXFLAT toolchain.
+  Builds an EABI ARM toolchain for the Cortex-M3 using gcc 4.6.3.
+  This configuration builds gcc, g++ and the NXFLAT toolchain.
 
 cortexm3-defconfig-nxflat
-arm926t-defconfig-nxflat
-	This configuration build an NXFLAT toolchain (only) for
-	use with the Cortex-M3 or ARM9 (untested on ARM9 as of this
-	writing).
-
-cortexm3-eabi-defconfig-4.5.2
-	Builds an EABI ARM toolchain for the Cortex-M3 using gcc 4.5.2.
-	This configuration builds gcc, g++ and the NXFLAT toolchain.
+  This configuration build an NXFLAT toolchain (only) for
+  use with the Cortex-M3.
 
 bfin-defconfig-4.2.4
-	Builds an Blackfin toolchain using gcc 4.2.4
+  Builds an Blackfin toolchain using gcc 4.2.4
 
 h8300_config
-	Builds an H8/300 toolchain using gcc 3.4.6
+  Builds an H8/300 toolchain using gcc 3.4.6
 
 i486-defconfig-4.3.3
-	Builds an i486 cross development toolchain using gcc 4.3.3.  Why would
-	you want such a thing?  On Linux, of course, such a thing is not needed
-	because you can use the installed GCC to build i486 ELF binaries.  But
-	that will not work under Cygwin!  The Cygwin toolchain (and probably
-	MinGW), build DOS MZ format executables (i.e., .exe files).  That is
-	probably not usable for most NuttX targets.  Instead, you should use this
-	i486-elf-gcc to generate true ELF binaries under Cygwin.
+  Builds an i486 cross development toolchain using gcc 4.3.3.  Why would
+  you want such a thing?  On Linux, of course, such a thing is not needed
+  because you can use the installed GCC to build i486 ELF binaries.  But
+  that will not work under Cygwin!  The Cygwin toolchain (and probably
+  MinGW), build DOS MZ format executables (i.e., .exe files).  That is
+  probably not usable for most NuttX targets.  Instead, you should use this
+  i486-elf-gcc to generate true ELF binaries under Cygwin.
 
 m32c_defconfig_4.2.4
 m32c_defconfig_4.3.3
-	Build a toolchain for use with the M16C port using eith gcc 4.2.4 or 4.3.3
+  Build a toolchain for use with the M16C port using eith gcc 4.2.4 or 4.3.3
 
 m68hc11-config
 m68hc12-config-3.4.6
-	Builds an hc11/hc12 toolchain using gcc 3.4.6 .  NOT RECOMMENDED for hcs12;
+  Builds an hc11/hc12 toolchain using gcc 3.4.6 .  NOT RECOMMENDED for hcs12;
     Use m9s12x_config_3.3.6
 
 m68hc12-config-4.3.3
-	Builds an hc11/hc12 toolchain using gcc 4.3.3.NOT RECOMMENDED for hcs12;
+  Builds an hc11/hc12 toolchain using gcc 4.3.3.NOT RECOMMENDED for hcs12;
     Use m9s12x_config_3.3.6
  
-	This configuration fails to build with the following error:
+  This configuration fails to build with the following error:
 
-	make[3]: Entering directory `blabla/buildroot/toolchain_build_m68hc12/gcc-4.3.3-build/m68hc12-elf/libgcc'
-	...
-	blabla/buildroot/toolchain_build_m68hc12/gcc-4.3.3/libgcc/../gcc/libgcc2.c:566: internal compiler error: in init_move_cost, at regclass.c:323
-	Please submit a full bug report,
-	with preprocessed source if appropriate.
-	See <http://gcc.gnu.org/bugs.html> for instructions.
-	make[3]: *** [_muldi3.o] Error 1
-	make[3]: Leaving directory `blabla/buildroot/toolchain_build_m68hc12/gcc-4.3.3-build/m68hc12-elf/libgcc'
+  make[3]: Entering directory `blabla/buildroot/toolchain_build_m68hc12/gcc-4.3.3-build/m68hc12-elf/libgcc'
+  ...
+  blabla/buildroot/toolchain_build_m68hc12/gcc-4.3.3/libgcc/../gcc/libgcc2.c:566: internal compiler error: in init_move_cost, at regclass.c:323
+  Please submit a full bug report,
+  with preprocessed source if appropriate.
+  See <http://gcc.gnu.org/bugs.html> for instructions.
+  make[3]: *** [_muldi3.o] Error 1
+  make[3]: Leaving directory `blabla/buildroot/toolchain_build_m68hc12/gcc-4.3.3-build/m68hc12-elf/libgcc'
 
-	Use m68hc12-config-3.4.6
+  Use m68hc12-config-3.4.6
 
 m9s12x_config_3.3.6
-	Builds a hcs12 toolchain using gcc 3.3.6 and extensive m9x12x-specific patches.
+  Builds a hcs12 toolchain using gcc 3.3.6 and extensive m9x12x-specific patches.
 
 m68k-config
-	Builds an M68K toolchain using gcc 3.4.6
+  Builds an M68K toolchain using gcc 3.4.6
 
 sh-defconfig
-	Builds an SH-1/2 toolchain using gcc 3.4.6
+  Builds an SH-1/2 toolchain using gcc 3.4.6
 
 GENERAL BUILD STEPS
 ^^^^^^^^^^^^^^^^^^^
@@ -282,14 +289,14 @@ Cygwin GCC BUILD NOTES
    and, apparently, the make variable "exeext" is set incorrectly.  A work around after the
    above occurs is:
 
-      cd toolchain_build_<arch>/gcc-4.2.4-build/gcc	# Go to the directory where error occurred
-      mv cc1-dummy.exe cc1-dummy			# Rename the executable without .exe
-      rm cc1-checksum.c					# Get rid of the bad generated file
+      cd toolchain_build_<arch>/gcc-4.2.4-build/gcc  # Go to the directory where error occurred
+      mv cc1-dummy.exe cc1-dummy         # Rename the executable without .exe
+      rm cc1-checksum.c                  # Get rid of the bad generated file
 
    Then resume the buildroot make:
 
-      cd -						# Back to the buildroot make directory
-      make						# Restart the build
+      cd -                               # Back to the buildroot make directory
+      make                               # Restart the build
 
    If you build g++, you will see another similar error:
 
@@ -300,14 +307,14 @@ Cygwin GCC BUILD NOTES
 
    The fix is similar:
 
-      cd toolchain_build_<arch>/gcc-4.2.4-build/gcc	# Go to the directory where error occurred
-      mv cc1plus-dummy.exe cc1plus-dummy		# Rename the executable without .exe
-      rm cc1plus-checksum.c				# Get rid of the bad generated file
+      cd toolchain_build_<arch>/gcc-4.2.4-build/gcc  # Go to the directory where error occurred
+      mv cc1plus-dummy.exe cc1plus-dummy # Rename the executable without .exe
+      rm cc1plus-checksum.c              # Get rid of the bad generated file
 
    Then resume the buildroot make:
 
-      cd -						# Back to the buildroot make directory
-      make						# Restart the build
+      cd -                               # Back to the buildroot make directory
+      make                               # Restart the build
 
  o Once I had problems building the toolchain on Cygwin.  In this case, I
    would occasioinally get "Permission denied" errors will trying to configure
@@ -341,4 +348,4 @@ Building GDB Under Cygwin
    directory if it is needed:
 
    cp configs/gdb-1_8-cygwin-1_7.patch toolchain/gdb/6.8/.
- 
+ 
\ No newline at end of file
diff --git a/misc/buildroot/configs/cortexm0-eabi-defconfig-4.6.3 b/misc/buildroot/configs/cortexm0-eabi-defconfig-4.6.3
new file mode 100644
index 000000000..663d548db
--- /dev/null
+++ b/misc/buildroot/configs/cortexm0-eabi-defconfig-4.6.3
@@ -0,0 +1,124 @@
+#
+# Automatically generated make config: don't edit
+#
+BR2_HAVE_DOT_CONFIG=y
+# BR2_alpha is not set
+BR2_arm=y
+# BR2_armeb is not set
+# BR2_avr is not set
+# BR2_avr32 is not set
+# BR2_bfin is not set
+# BR2_cris is not set
+# BR2_i386 is not set
+# BR2_m32c is not set
+# BR2_m68k is not set
+# BR2_m68hc11 is not set
+# BR2_m68hc12 is not set
+# BR2_m9s12x is not set
+# BR2_mips is not set
+# BR2_mipsel is not set
+# BR2_nios2 is not set
+# BR2_powerpc is not set
+# BR2_sh is not set
+# BR2_sh64 is not set
+# BR2_h8300 is not set
+# BR2_sparc is not set
+# BR2_x86_64 is not set
+# BR2_generic_arm is not set
+# BR2_arm610 is not set
+# BR2_arm7tdmi is not set
+# BR2_arm710 is not set
+# BR2_arm720t is not set
+# BR2_arm740t is not set
+# BR2_arm920t is not set
+# BR2_arm922t is not set
+# BR2_arm926t is not set
+# BR2_arm1136jf_s is not set
+# BR2_cortex_m3 is not set
+BR2_cortex_m0=y
+# BR2_sa110 is not set
+# BR2_sa1100 is not set
+# BR2_xscale is not set
+# BR2_iwmmxt is not set
+# BR2_ARM_OABI is not set
+BR2_ARM_EABI=y
+BR2_ARCH="arm"
+BR2_GCC_TARGET_TUNE="cortex-m0"
+BR2_GCC_TARGET_ARCH="armv6-m"
+BR2_GCC_TARGET_ABI="aapcs-linux"
+BR2_ENDIAN="LITTLE"
+
+#
+# Build options
+#
+BR2_WGET="wget --passive-ftp"
+BR2_SVN="svn co"
+BR2_ZCAT="zcat"
+BR2_BZCAT="bzcat"
+BR2_TAR_OPTIONS=""
+BR2_DL_DIR="$(BASE_DIR)/../archives"
+BR2_STAGING_DIR="$(BUILD_DIR)/staging_dir"
+BR2_NUTTX_DIR="$(TOPDIR)/../../nuttx"
+BR2_TOPDIR_PREFIX=""
+BR2_TOPDIR_SUFFIX=""
+BR2_GNU_BUILD_SUFFIX="pc-elf"
+BR2_GNU_TARGET_SUFFIX="nuttx-eabi"
+# BR2_PREFER_IMA is not set
+
+#
+# Toolchain Options
+#
+
+#
+# Binutils Options
+#
+# BR2_BINUTILS_VERSION_2_17 is not set
+# BR2_BINUTILS_VERSION_2_18 is not set
+# BR2_BINUTILS_VERSION_2_19 is not set
+# BR2_BINUTILS_VERSION_2_19_1 is not set
+# BR2_BINUTILS_VERSION_2_21_1 is not set
+BR2_BINUTILS_VERSION_2_22=y
+BR2_BINUTILS_VERSION="2.22"
+BR2_EXTRA_BINUTILS_CONFIG_OPTIONS=""
+
+#
+# GCC Options
+#
+BR2_PACKAGE_GCC=y
+# BR2_GCC_VERSION_3_3_6 is not set
+# BR2_GCC_VERSION_3_4_6 is not set
+# BR2_GCC_VERSION_4_2_4 is not set
+# BR2_GCC_VERSION_4_3_3 is not set
+# BR2_GCC_VERSION_4_5_2 is not set
+BR2_GCC_VERSION_4_6_3=y
+BR2_GCC_SUPPORTS_SYSROOT=y
+BR2_GCC_VERSION="4.6.3"
+# BR2_GCC_USE_SJLJ_EXCEPTIONS is not set
+BR2_EXTRA_GCC_CONFIG_OPTIONS=""
+BR2_INSTALL_LIBSTDCPP=y
+# BR2_INSTALL_LIBGCJ is not set
+# BR2_INSTALL_OBJC is not set
+# BR2_INSTALL_FORTRAN is not set
+
+#
+# Gdb Options
+#
+# BR2_PACKAGE_GDB is not set
+# BR2_PACKAGE_GDB_SERVER is not set
+# BR2_PACKAGE_GDB_HOST is not set
+
+#
+# NuttX Binary Support
+#
+# BR2_PACKAGE_NXFLAT is not set
+BR2_PACKAGE_GENROMFS=y
+
+#
+# Common Toolchain Options
+#
+# BR2_PACKAGE_SSTRIP_TARGET is not set
+# BR2_PACKAGE_SSTRIP_HOST is not set
+# BR2_ENABLE_MULTILIB is not set
+BR2_LARGEFILE=y
+BR2_SOFT_FLOAT=y
+BR2_TARGET_OPTIMIZATION="-Os -pipe"
diff --git a/misc/buildroot/toolchain/binutils/Config.in b/misc/buildroot/toolchain/binutils/Config.in
index 028ac0412..96cff013f 100644
--- a/misc/buildroot/toolchain/binutils/Config.in
+++ b/misc/buildroot/toolchain/binutils/Config.in
@@ -4,23 +4,23 @@ comment "Binutils Options"
 
 choice
 	prompt "Binutils Version"
-	default BR2_BINUTILS_VERSION_2_19_1 if BR2_cortex_m3
-	default BR2_BINUTILS_VERSION_2_19 if !BR2_avr32 && !BR2_cortex_m3 && !BR2_m9s12x
+	default BR2_BINUTILS_VERSION_2_19_1 if BR2_cortex_m3 || BR2_cortex_m0
+	default BR2_BINUTILS_VERSION_2_19 if !BR2_avr32 && !BR2_cortex_m3 && !BR2_cortex_m0 && !BR2_m9s12x
 	default BR2_BINUTILS_VERSION_2_18 if BR2_m9s12x
-	default BR2_BINUTILS_VERSION_2_17 if !BR2_cortex_m3 && !BR2_m9s12x
+	default BR2_BINUTILS_VERSION_2_17 if !BR2_cortex_m3 && !BR2_cortex_m0 && !BR2_m9s12x
 	help
 	  Select the version of binutils you wish to use.
 
 	config BR2_BINUTILS_VERSION_2_17
-		depends !BR2_nios2 && !BR2_cortex_m3 && !BR2_m9s12x
+		depends !BR2_nios2 && !BR2_cortex_m3 && !BR2_cortex_m0 && !BR2_m9s12x
 		bool "binutils 2.17"
 
 	config BR2_BINUTILS_VERSION_2_18
-		depends !BR2_avr32 && !BR2_nios2 && !BR2_cortex_m3
+		depends !BR2_avr32 && !BR2_nios2 && !BR2_cortex_m3 && !BR2_cortex_m0
 		bool "binutils 2.18"
 
 	config BR2_BINUTILS_VERSION_2_19
-		depends !BR2_avr32 && !BR2_nios2 && !BR2_cortex_m3 && !BR2_m9s12x
+		depends !BR2_avr32 && !BR2_nios2 && !BR2_cortex_m3 && !BR2_cortex_m0 &&!BR2_m9s12x
 		bool "binutils 2.19"
 
 	config BR2_BINUTILS_VERSION_2_19_1
diff --git a/misc/buildroot/toolchain/gcc/Config.in b/misc/buildroot/toolchain/gcc/Config.in
index 822cfd4b9..edef88a3e 100644
--- a/misc/buildroot/toolchain/gcc/Config.in
+++ b/misc/buildroot/toolchain/gcc/Config.in
@@ -10,8 +10,8 @@ config BR2_PACKAGE_GCC
 
 choice
 	prompt "GCC compiler Version"
-	default BR2_GCC_VERSION_4_3_3 if BR2_cortex_m3
-	default BR2_GCC_VERSION_4_2_4 if !BR2_avr32 && !BR2_cortex_m3 && !BR2_m9s12x
+	default BR2_GCC_VERSION_4_3_3 if BR2_cortex_m3 || BR2_cortex_m0
+	default BR2_GCC_VERSION_4_2_4 if !BR2_avr32 && !BR2_cortex_m3 && !BR2_cortex_m0 && !BR2_m9s12x
 	default BR2_GCC_VERSION_3_4_6 if BR2_avr32
 	default BR2_GCC_VERSION_3_3_6 if BR2_m9s12x
 	depends on BR2_PACKAGE_GCC
@@ -23,11 +23,11 @@ choice
 		bool "gcc 3.3.6"
 
     config BR2_GCC_VERSION_3_4_6
-		depends on !BR2_m32c && !BR2_cortex_m3 && !BR2_m9s12x
+		depends on !BR2_m32c && !BR2_cortex_m3 && !BR2_cortex_m0 && !BR2_m9s12x
 		bool "gcc 3.4.6"
 
 	config BR2_GCC_VERSION_4_2_4
-		depends on !BR2_avr32 && !BR2_nios2 && !BR2_cortex_m3 && !BR2_m9s12x
+		depends on !BR2_avr32 && !BR2_nios2 && !BR2_cortex_m3 && !BR2_cortex_m0 && !BR2_m9s12x
 		select BR2_GCC_SUPPORTS_SYSROOT
 		bool "gcc 4.2.4"
 
diff --git a/misc/buildroot/toolchain/gcc/Makefile.in b/misc/buildroot/toolchain/gcc/Makefile.in
index aaec774dc..7ae07cfe8 100644
--- a/misc/buildroot/toolchain/gcc/Makefile.in
+++ b/misc/buildroot/toolchain/gcc/Makefile.in
@@ -57,6 +57,9 @@ ifneq ($(strip $(subst ",,$(BR2_GCC_TARGET_ABI))),)
 # ")))
 GCC_WITH_ABI:=--with-abi=$(BR2_GCC_TARGET_ABI)
 endif
+ifdef BR2_cortex_m0
+GCC_WITH_MODE:=--with-mode=thumb
+endif
 ifdef BR2_cortex_m3
 GCC_WITH_MODE:=--with-mode=thumb
 endif