ARM: let CPUs not being able to run in ARM mode enter in THUMB mode

Some ARM cores are not capable to run in ARM mode (e.g. Cortex-M3). So
obviously these cannot enter the kernel in ARM mode. Make an exception
for them and let them enter in THUMB mode.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Message-Id: 1358162123-30113-1-git-send-email-u.kleine-koenig@pengutronix.de
Acked-by: Nicolas Pitre <nico@linaro.org>

1 files changed, 8 insertions, 1 deletions

diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index 3fd629d5a513..8defd638c79e 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -397,6 +397,13 @@ config CPU_V7
         select CPU_PABRT_V7
         select CPU_TLB_V7 if MMU
 
+config CPU_THUMBONLY
+        bool
+        # There are no CPUs available with MMU that don't implement an ARM ISA:
+        depends on !MMU
+        help
+          Select this if your CPU doesn't support the 32 bit ARM instructions.
+
 # Figure out what processor architecture version we should be using.
 # This defines the compiler instruction set which depends on the machine type.
 config CPU_32v3
@@ -608,7 +615,7 @@ config ARCH_DMA_ADDR_T_64BIT
         bool
 
 config ARM_THUMB
-        bool "Support Thumb user binaries"
+        bool "Support Thumb user binaries" if !CPU_THUMBONLY
         depends on CPU_ARM720T || CPU_ARM740T || CPU_ARM920T || CPU_ARM922T || CPU_ARM925T || CPU_ARM926T || CPU_ARM940T || CPU_ARM946E || CPU_ARM1020 || CPU_ARM1020E || CPU_ARM1022 || CPU_ARM1026 || CPU_XSCALE || CPU_XSC3 || CPU_MOHAWK || CPU_V6 || CPU_V6K || CPU_V7 || CPU_FEROCEON
         default y
         help