[Buildroot] [PATCH] arch/arm: add support for thumb(1) mode

Thomas Petazzoni thomas.petazzoni at free-electrons.com
Thu Jul 18 07:19:17 UTC 2013


Dear Gustavo Zacarias,

On Wed, 17 Jul 2013 19:25:24 -0300, Gustavo Zacarias wrote:
> On 07/17/2013 04:58 PM, Thomas Petazzoni wrote:
> 
> > Ok, so if I select "Thumb" for ARMv5T, but use a normal ARMv5
> > external toolchain (compiled ARM, not Thumb), it should work. Am I
> > correct?
> 
> Yes, because at the moment it's a NOP, we don't do anything regarding
> thumb and external toolchains :)

We definitely do something. If you enable Thumb in the configuration,
then -mthumb gets hard-coded into the external toolchain wrapper. If you
enable ARM in the configuration, then -marm gets hard-coded into the
external toolchain wrapper.

See:
http://git.buildroot.net/buildroot/tree/toolchain/toolchain-external/ext-tool.mk#n183
and:
http://git.buildroot.net/buildroot/tree/toolchain/toolchain-external/ext-toolchain-wrapper.c#n50.

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com


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