[oe] iwmmxt optimization and soft float in OE on PXA270

[Stanislav Brabec]

Hasjim Williams wrote:

> You won't be able to use iwmmxt with everything.  The unwind / exception
> support for iwxmmt isn't there in gcc.  Anything using C++ exceptions
> won't work correctly.

So plain C binaries (e. g. kernel) are OK? And
c++ -march=iwmmxt -fno-exceptions as well?

> infocenter.arm.com/help/topic/com.arm.doc.ihi0038a/IHI0038A_ehabi.pdf
> explains about the unwind / exceptions.
> 
> This is also one of the issues that Cirrus's MaverickCrunch currently
> has.
> 
> The only ARM coprocessor that is fully supported (by gcc) is VFP.  
> 
> In summary, we'd have to modify:
> gcc/config/arm/pr-support.c
> gcc/config/arm/unwind-arm.h
> gcc/config/arm/unwind-arm.c
> 
> for proper iwmmxt Unwind_VRS_Pop support.
> 
> NB, I'm the guy that has done the MaverickCrunch gcc patches...
> 
> I could write/test these patches, I guess, but the only PXA270 machine
> that I have access to is a HTC Magician (XDA Mini).

It would be very nice. I could test them on my Zaurus, if you send me
some C++ testcase (or name of application to test it on).

The last missing thing - iwmmxt support in qemu - was already written by
Andrzej Zaborowski.

-- 
Stanislav Brabec
http://www.penguin.cz/~utx/zaurus