APU FPU in Virtex ppc405

Ron Sass rsass at uncc.edu
Fri May 23 11:26:31 EST 2008

Shan and I are going to sit down and rebuild our tool chain (a mix
of crosstool, linux-from-scratch, and Xilinx patches) next week.
Our aim is to quantify the gains/losses of frequency versus
hardware acceleration since we have several large scientific apps
we plan to run.  Like he said, we're hoping to have a handle on
the best approach over the next couple of weeks.


> My understanding is that with the fpu on the ppc405 (not ppc440), the
> processor clock rate had to be reduced for the fpu to work. This ended
> up negating much of the performance benefits of using the fpu.
> I don't know the specifics offhand, but Xilinx answer records can be
> searched. Hopefully I'm wrong, and there can still be a benefit to using
> the ppc405 fpu.
> - John
> On Thu, 2008-05-22 at 19:06 -0400, David H. Lynch Jr. wrote:
> >    Were the issues associated with getting the Xilinx Floating point APU
> > working with Linux completely resolved ?
> >     Is there a git tree or patch collection with the appropriate patches
> > etc ?
> > 
> > 
> > 

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