[Buildroot] [git commit] arch/arm: Cortex-M3 provides only Thumb-2

Thomas Petazzoni thomas.petazzoni at free-electrons.com
Sun Mar 20 14:37:24 UTC 2016


commit: https://git.buildroot.net/buildroot/commit/?id=41bcc440b1a4a85530b45c2b2a30662e6a823b75
branch: https://git.buildroot.net/buildroot/commit/?id=refs/heads/master

The Cortex-M cores only support Thumb-2, not Thumb. In fact, Thumb-2
is a superset of Thumb, and we could have a single option for both in
Buildroot, since -mthumb on ARMv4/v5 means original Thumb, while
-mthumb on ARMv7 means Thumb 2. However, for clarity, it makes sense
to have two separate options. But in this case, Cortex-M3 should not
advertise that it supports Thumb, as in fact selecting Thumb would
generate Thumb-2 code.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998 at free.fr>
Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout at mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
---
 arch/Config.in.arm | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/Config.in.arm b/arch/Config.in.arm
index 33f763a..cd1ec33 100644
--- a/arch/Config.in.arm
+++ b/arch/Config.in.arm
@@ -172,7 +172,6 @@ config BR2_cortex_a17
 	select BR2_ARCH_HAS_MMU_OPTIONAL
 config BR2_cortex_m3
 	bool "cortex-M3"
-	select BR2_ARM_CPU_HAS_THUMB
 	select BR2_ARM_CPU_HAS_THUMB2
 	select BR2_ARM_CPU_ARMV7M
 config BR2_fa526


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