Re: Bonehead floating-point question

On Thu, 13 Mar 2003 10:39:34 -0800
David Wuertele <dave-gnus@xxxxxxxxx> wrote:

> OK, I have a totally basic floating-point question for y'all.
> 
> I've been trying to compile everything "soft float" and I've been
> having a lot of trouble.  Now I find out about the floating point
> emulator that comes with every kernel.  In fact, my kernel has that
> compiled in by default, and reports "Algorithmics/MIPS FPU Emulator
> v1.5" when it boots.
> 
> What is the relationship between compiling for my target with
> -msoft-float and the target kernel's floating point emulator?  If I've
> got an emulator, why should I do anything with soft floats?
> 
> For example, uClibc Configuration asks at one point:
> 
>   Target CPU has a floating point unit (FPU) (HAS_FPU) [Y/n/?] y
> 
> Why should it care?  As a matter of fact my target CPU does *not* have
> an FPU, but since I've got emulation it shouldn't matter.  What do I
> gain/loose by saying "n" here?
> 
> The default buildroot builds gcc "--without-float" ... Why is that
> needed?
> 
> Thanks,
> Dave
> 
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I am not sure on this but I think the uClibc soft float maybe smaller. I don't 
know what you looking to do with your kernel but if you expect to put it on a 
small device or even a floppy dropping floating poit EMU in the kernel will 
save you tons of space.