Re: [ECOS] Re: Ecos Port to PPC509/PPC555

[Jonathan Larmour <jlarmour@cygnus.co.uk>]

Sergei Organov wrote:
> 
> No, I'd better build all eCos with -mhard-float. The only significant
> trouble is 'printf' and friends where FP code isn't separated from
> non-FP, and thus generated code contains FP registers save/restore in
> prologue and epilogue.

As Bart pointed out to me in person earlier, the calling conventions will be
screwed up when calling to/from a module compiled with -msoft-float from/to
a module compiled with -mhard-float.

So I think trying to mix types of code built with these options is probably
a lost cause I'm afraid.

And getting gcc not to use the FP registers under any circumstances is only
an "optimization" really, especially since it seems to only happen under
extreme register pressure. The worst that can happen is unnecessary FP
context saves.

However I think your detailed proposal looks sound in principle. Our kernel
guru is just back from a two-week holiday and should be able to comment when
he gets to the bottom of his e-mail (which may take some time!). We won't be
forgetting you :-).

Jifl
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