[PATCH] arm: simplify handling of Thumb related options

[Rich Felker]

On Sun, Mar 20, 2016 at 05:58:35PM +0100, Thomas Petazzoni wrote:
> Currently, the Thumb support on ARM has three related Config.in
> options, which are not trivial for users to understand, and are in
> fact not needed:
> 
>  - The USE_BX option is not needed: knowing whether BX is available or
>    not is easy. If you have an ARM > v4 or ARMv4T, then BX is
>    available, otherwise it's not. This is the logic used in glibc.

This sounds correct.

>  - The USE_LDREXSTREX option is not needed: whenever Thumb2 is
>    available, ldrex/strex are available, so we can simply rely on
>    __thumb2__ to determine whether ldrex/strex should be used, without
>    requiring a Config.in option.

__thumb2__ is sufficient for ldrex/strex but not sufficient; v6 has
them in the arm isa. Or does logic only apply when you've selected to
use thumb?

Rich