[Buildroot] [PATCH] arch/arm: use EABIhf by default with VFP

[Benoît Thébaudeau]

On Sun, Oct 25, 2015 at 9:40 PM, Peter Korsgaard <peter at korsgaard.com> wrote:
>>>>>> "Benoît" == Benoît Thébaudeau <benoit.thebaudeau.dev at gmail.com> writes:
>
>  > On Sun, Oct 25, 2015 at 7:55 PM, Peter Korsgaard <peter at korsgaard.com> wrote:
>  >>>>>>> "Benoît" == Benoît Thébaudeau <benoit.thebaudeau.dev at gmail.com> writes:
>  >>
>  >> > Set EABIhf as the default target ABI for the ARM processors that have or
>  >> > may have a VFP unit, since this ABI is the most efficient in that case.
>  >> > Of course, EABI can still be selected manually if needed.
>  >>
>  >> On a related note, should we default to thumb2 if the CPU supports it?
>
>  > I would say:
>
>  >     choice
>  >            prompt "ARM instruction set"
>  >            default BR2_ARM_INSTRUCTIONS_ARM if BR2_ARM_CPU_HAS_ARM
>  >            default BR2_ARM_INSTRUCTIONS_THUMBS2 if BR2_ARM_CPU_HAS_THUMBS2
>  >            default BR2_ARM_INSTRUCTIONS_THUMBS if BR2_ARM_CPU_HAS_THUMBS
>
> I'm not sure it makes sense to default to thumb1 even if the CPU
> supports it because of various compatibility issues

It's the first default that wins, not the last one, so above it's ARM
over Thumb1.

> - So simply:
>
> default BR2_ARM_INSTRUCTIONS_THUMBS2 if BR2_ARM_CPU_HAS_THUMBS2
>
> (if no thumb2 is available, the first available option (ARM) is used).

With ARM + Thumb2, I would rather use ARM to avoid compatibility
issues, except on platforms very constrained on memory. On Cortex-M3,
there's not even ARM. Or is it common to use Thumb2 on bigger
platforms like Cortex-A*?

Best regards,
Benoît