more patches more newlib-1.16.0 : setjmp & longjmp for 4.9 branch

[Ralf Corsepius]

Till Straumann wrote:
> IIRC I had contributed a (maybe similar) patch in the past
> which addressed saving/restoring FP context as part of
> setjmp/longjmp.

I vaguely recall you patches - IIRC, they lacked generality because of 
the same issues as being raised here.


> Indeed, there were __rtems__ specific pieces:
> 
>  - on rtems not all threads are necessarily FP-enabled
>  - on rtems lazy-FP context switching is possible
>  - on rtems we can read MSR to find out if the FPU is
>    enabled or not (since we run in supervisory mode).

This doesn't parse to anything I understand.

> -> my patch (#ifdef __rtems__ only) used the MSR[FE]
>    information to dump/load FP registers when possible/necessary.
> 
> Under these premises the test for __rtems__ seems to
> make sense but you might have a better idea.
First of all, I need to understand these patches. So far, even with your 
attempts to explain, this hasn't happened.

Ralf