Subject: Re: floating point operation of ppc

From: Eugene Surovegin <[email-masked]>
Date: Fri, 11 Nov 2005 11:35:16 -0800

On Fri, Nov 11, 2005 at 07:51:31AM -0500, Greg Weeks wrote:
> lily wrote:
> 
> > hi,all:
> > i build an embedded linux on powerpc 405ep,i need execute floating
> > point operation,and i enable "math emulate" option in kernel, i run a
> > while(1)loop ,in the loop there was floating point expression ,after
> > test ,i found the while (1) exit because of the floating point
> > computation,that is the floating point can't execute on ppc
> > stablely.Is there someone meets the same problems ,please give me some
> > suggestion,thanks!!!
> 
> The 405ep has some errata on floating point use. 

Are you sure it was 405ep? There is no floating point errata for this 
chip due to the simple reason, it doesn't support floating point in 
hardware at all.

You probably confusing it with 440ep.

I'm not aware of any 405ep specific toolchain. In fact, all what is 
needed is simple 4xx specific toolchain with soft-float enabled by 
default. This is how floating point is usually done for 4xx - just soft 
emulation in user-space by the compiler without in-kernel emulation, 
which is slow.

-- 
Eugene