APU FPU in Virtex ppc405

APU FPU in Virtex ppc405

[A. Nolson]

Hi,

 I have just heard that Xilinx has freed the FPU module for the PPC 
architecture in EDK9.2i. WIll I be able to make it work with my 
Secretlab Linux 2.6.24rc3? Will the eldk toolchain for PPC_4xxfp work? 
Will it be just a matter of integrating it with the XPS BSP?I make an 
extensive use of floating point in my applications and this will be 
really useful.

 Thanks for your help.

Re: APU FPU in Virtex ppc405

[Grant Likely]

On Feb 8, 2008 11:51 AM, A. Nolson <alohanono@gmail.com> wrote:
> Hi,
>
>  I have just heard that Xilinx has freed the FPU module for the PPC
> architecture in EDK9.2i. WIll I be able to make it work with my
> Secretlab Linux 2.6.24rc3? Will the eldk toolchain for PPC_4xxfp work?
> Will it be just a matter of integrating it with the XPS BSP?I make an
> extensive use of floating point in my applications and this will be
> really useful.

It's been 2 years since I last played with the FPU core.  At the time
it wasn't a complete FPU so the eldk 4xxfp toolchain would not work.
I had to build my own.  I don't know if the new core is a complete
implementation.

Cheers,
g.


-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.

Re: APU FPU in Virtex ppc405

[A. Nolson]

I have been checking and it seems that the APU FPU patches will give 
some headaches now, so I will probably wait until they merge them with 
the official GCC release. In any case, it seems that the FPU restricts 
the PowerPC and bus frequencies to a max of 200/100.

Anyway, thanks for the info. I will try to keep track of this in case of 
an update.

Grant Likely wrote:
> On Feb 8, 2008 11:51 AM, A. Nolson <alohanono@gmail.com> wrote:
>   
>> Hi,
>>
>>  I have just heard that Xilinx has freed the FPU module for the PPC
>> architecture in EDK9.2i. WIll I be able to make it work with my
>> Secretlab Linux 2.6.24rc3? Will the eldk toolchain for PPC_4xxfp work?
>> Will it be just a matter of integrating it with the XPS BSP?I make an
>> extensive use of floating point in my applications and this will be
>> really useful.
>>     
>
> It's been 2 years since I last played with the FPU core.  At the time
> it wasn't a complete FPU so the eldk 4xxfp toolchain would not work.
> I had to build my own.  I don't know if the new core is a complete
> implementation.
>
> Cheers,
> g.
>
>
>   

Re: APU FPU in Virtex ppc405

[Thomas Werne]

A. Nolson <alohanono <at> gmail.com> writes:

> 
> I have been checking and it seems that the APU FPU patches will give 
> some headaches now, so I will probably wait until they merge them with 
> the official GCC release. In any case, it seems that the FPU restricts 
> the PowerPC and bus frequencies to a max of 200/100.
> 
> Anyway, thanks for the info. I will try to keep track of this in case of 
> an update.
> 

Hi -

You can get the FPU to work with the 2.6.24rc3 Linux (I got it to work just
yesterday).  There are a couple of small changes you have to make to kernel
config files and to one of the .h files, plus you need to compile with the
-fshort-double flag to convert all doubles into floats.  Let me know if you're
still interested and I can post details and/or patches.

Thomas

--
Thomas Werne
NASA Jet Propulsion Laboratory

All personal and professional opinions presented herein are my
own and do not, in any way, represent the opinion or policy of JPL.

Re: APU FPU in Virtex ppc405

[A. Nolson]

Hi Thomas,

 I am still very interested in this. It would be really good if you can 
post what you have so far. Did you also have to patch gcc also? Is there 
any penalty in performance when compiling with -fshort-double?

 /Albert

Thomas Werne wrote:
> A. Nolson <alohanono <at> gmail.com> writes:
>
>   
>> I have been checking and it seems that the APU FPU patches will give 
>> some headaches now, so I will probably wait until they merge them with 
>> the official GCC release. In any case, it seems that the FPU restricts 
>> the PowerPC and bus frequencies to a max of 200/100.
>>
>> Anyway, thanks for the info. I will try to keep track of this in case of 
>> an update.
>>
>>     
>
> Hi -
>
> You can get the FPU to work with the 2.6.24rc3 Linux (I got it to work just
> yesterday).  There are a couple of small changes you have to make to kernel
> config files and to one of the .h files, plus you need to compile with the
> -fshort-double flag to convert all doubles into floats.  Let me know if you're
> still interested and I can post details and/or patches.
>
> Thomas
>
> --
> Thomas Werne
> NASA Jet Propulsion Laboratory
>
> All personal and professional opinions presented herein are my
> own and do not, in any way, represent the opinion or policy of JPL.
>
>
> _______________________________________________
> Linuxppc-embedded mailing list
> Linuxppc-embedded@ozlabs.org
> https://ozlabs.org/mailman/listinfo/linuxppc-embedded
>
>   

APU FPU in Virtex ppc405

[David H. Lynch Jr.]

   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 ?



-- 
Dave Lynch 					  	    DLA Systems
Software Development:  				         Embedded Linux
717.627.3770 	       dhlii@dlasys.net 	  http://www.dlasys.net
fax: 1.253.369.9244 			           Cell: 1.717.587.7774
Over 25 years' experience in platforms, languages, and technologies too numerous to list.

"Any intelligent fool can make things bigger and more complex... It takes a touch of genius - and a lot of courage to move in the opposite direction."
Albert Einstein

Re: APU FPU in Virtex ppc405

[Grant Likely]

On Thu, May 22, 2008 at 5:06 PM, David H. Lynch Jr. <dhlii@dlasys.net> 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 ?

I had it working at one point ages ago, but that project ended up
dropping the work and I haven't touched it since.  I think I posted
the patches but I don't have a link to them easily at hand.

Cheers,
g.

-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.

Re: APU FPU in Virtex ppc405

[Shanyuan Gao]

Yes, it's working under Linux.  Just do as John, Steve, and Yoshio  
suggest.  That should work then.  My problem was that our own cross- 
tool was not working correctly.  But we will fix it in next couple of  
weeks.

I did very primitive changes and didn't have a patch.  In next few  
weeks we might want to go for powerpc tree then, so  I will try to do  
it all over again.



Shan


On May 22, 2008, at 7:06 PM, 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 ?
>
>
>
> -- 
> Dave Lynch 					  	    DLA Systems
> Software Development:  				         Embedded Linux
> 717.627.3770 	       dhlii@dlasys.net 	  http://www.dlasys.net
> fax: 1.253.369.9244 			           Cell: 1.717.587.7774
> Over 25 years' experience in platforms, languages, and technologies  
> too numerous to list.
>
> "Any intelligent fool can make things bigger and more complex... It  
> takes a touch of genius - and a lot of courage to move in the  
> opposite direction."
> Albert Einstein
>

Re: APU FPU in Virtex ppc405

[John Bonesio]

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 ?
> 
> 
> 

________________________________________________________________________

John Bonesio
Commercial Linux Solutions
john.bonesio@xilinx.com
(408) 879-5569

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Re: APU FPU in Virtex ppc405

[Ron Sass]

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.

Ron

> 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 ?
> > 
> > 
> > 
>