cross-gcc : FPU type error

Marius Groeger mgroeger@sysgo.com
Wed May 26 15:40:00 GMT 2004


Hi Dimitry,

On Wed, 26 May 2004, Dimitry Andric wrote:

> Yup, running glibc + all apps with softfloat, VFP format.  However,

What is "all apps" in your project? If you go all the way up to X11,
this can be quite a lot...

> since the kernel shouldn't use any floating point anyway, I'm not very
> sure why they added -msoft-float to the compilation options.  For
> kernel compiles, it would be nice to have a -Werror-on-fp option, or
> something like that.

Actually, -msoft-float in kernel or firmware Makefiles usually means
"no float operations, please". I'm not sure about ARM, but on PPC, the
compiler likes to use FP registers for optimization purposes.
Throwing -msoft-float prevents this.

I agree that a -Werror-on-fp option would be nice. But don't forget
that to be really sure, you'd need that on the linker level to catch
malicious asm sources or inline asm as well!

Regards,
Marius

-- 
Marius Groeger <mgroeger@sysgo.com>           Project Manager
SYSGO AG                      Embedded and Real-Time Software
Voice: +49 6136 9948 0                  FAX: +49 6136 9948 10
www.sysgo.com | www.elinos.com | www.osek.de | www.imerva.com


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