mpc5200b and floating point

mpc5200b and floating point

[Sascha Hauer]

Hi,

I'm working with a mpc5200b custom board and I'm trying to run an
application with floating point. All floating point variables seem to
zero all the time. Since I'm not very familiar with powerpc it might be
something stupid I have overlooked.
Any hints?

Thank you,

  Sascha Hauer

Re: mpc5200b and floating point

[Roger Larsson]

On fredag 31 mars 2006 15.36, Sascha Hauer wrote:
> Hi,
>
> I'm working with a mpc5200b custom board and I'm trying to run an
> application with floating point. All floating point variables seem to
> zero all the time. Since I'm not very familiar with powerpc it might be
> something stupid I have overlooked.

Since a lot of PowerPC do not have floating point processor your tools
might be setup to compile without it (compare with sse2 on x86).

Check your compiler flags again.
Define -mcpu= and -mhard-float
Undefine -msoft-float

/RogerL

Re: mpc5200b and floating point

[White]

Am Fri, 31 Mar 2006 15:36:20 +0200 schrieb Sascha Hauer
<s.hauer@pengutronix.de> :

Please check your Toolchain.
Have you build it ?

Do you use glibc or something like uclibc ?

At my beginning with mpc5200 i hat simular problems.

I had the wrong Compilerflags during build of my ToolChain.
(uclibc).

Good Luck.

> Hi,
> 
> I'm working with a mpc5200b custom board and I'm trying to run an
> application with floating point. All floating point variables seem to
> zero all the time. Since I'm not very familiar with powerpc it might be
> something stupid I have overlooked.
> Any hints?
> 
> Thank you,
> 
>   Sascha Hauer
> 
> _______________________________________________
> Linuxppc-embedded mailing list
> Linuxppc-embedded@ozlabs.org
> https://ozlabs.org/mailman/listinfo/linuxppc-embedded
> 

Re: mpc5200b and floating point

[Dan Malek]

On Mar 31, 2006, at 1:27 PM, Roger Larsson wrote:

> Since a lot of PowerPC do not have floating point processor your tools
> might be setup to compile without it (compare with sse2 on x86).

Nearly all of the PowerPC do have floating point, only a few do not.
It's highly unlikely to find a PowerPC tool set that was custom
built to not enable floating point.  Don't forget that the compiler
flags are only a small part of the picture, you need matching
compiler run time support and application libraries as well.
Just using the compiler flags and not selecting the proper
libraries will not be a positive experience.


	-- Dan

Re: mpc5200b and floating point

[Sascha Hauer]

On Fri, Mar 31, 2006 at 08:36:34PM +0200, White wrote:
> Am Fri, 31 Mar 2006 15:36:20 +0200 schrieb Sascha Hauer
> <s.hauer@pengutronix.de> :
> 
> Please check your Toolchain.
> Have you build it ?

I have built it with crosstool 0.38

> 
> Do you use glibc or something like uclibc ?

glibc

With -msoft-float everything is working fine, but with softfloat.
Without flags or with -mhard-float my toolchain (which is btw a
gcc-4.0.2, glibc 2.3.6) generates floating point instructions which I
can see in the objdump.
Since this seems more like a toolchain related problem, maybe the
crosstool ml is a better place for this.

Sascha

Re: mpc5200b and floating point

[Sascha Hauer]

On Fri, Mar 31, 2006 at 03:36:20PM +0200, Sascha Hauer wrote:
> Hi,
> 
> I'm working with a mpc5200b custom board and I'm trying to run an
> application with floating point. All floating point variables seem to
> zero all the time. Since I'm not very familiar with powerpc it might be
> something stupid I have overlooked.
> Any hints?

The problem turned out to be toolchain related. We chrooted into the
rootfs on an Ibook, same problem there. I'll take a closer look in my
toochain.

Thank you for your replies,

Sascha Hauer