[uclibc-ng-devel] [PATCH] arm: simplify handling of Thumb related options

Waldemar Brodkorb wbx at uclibc-ng.org
Thu Mar 31 17:46:21 UTC 2016


Hi Thomas,
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.
> 
>  - 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.
> 
>  - Once USE_BX and USE_LDREXSTREX are removed, the only thing left
>    that COMPILE_IN_THUMB does is to set -mthumb. This makes the option
>    unnecessary, as on ARM at least, the user is already supposed to
>    pass -march=<foo> or other compiler options tuning the library for
>    a specific ARM variant. There is no reason to do otherwise for
>    Thumb, which allows to get rid of the COMPILE_IN_THUMB option.
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>

Applied and pushed.

Want to get the thread ARM noMMU problem analyzed and fixed before
the next release. Did you done any further testing?

 best regards
  Waldemar


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