Floating point on IBM PPC405 (266MHz)

Yes. PPC405GPr.

Yes, because the PPC405 has no floating point support.

Hope that helps JB

--
Juergen Beisert        email: jbeisert _AT_ eurodsn _DOT_ de
EuroDesign embedded technologies GmbH  http://www.eurodsn.de

In any case, you should make sure you are using a proper toolchain that does not generate floating point instructions (ie. implies a -fsoft-float). These can be handled by the kernel's math emulation, but this will slow things down even more.

Regards, Marius.

-- Marius Groeger SYSGO Real-Time Solutions GmbH

Software Engineering Embedded and Real-Time Software mgroeger @ sysgo de Germany

We're using the PPC405, too. I never got the kernel's floating point emulation to work, so we're 100% soft-float. I have a toolchain build script at

that handles that right. No idea about performance, though; soft float probably sucks.

- Dan

Well, compared to kernel emulation it doesn't suck. It would suck to have to trap every time you needed to emulate a FP instruction. :)

If somebody needs good FP performance on 4xx then they could buy (in huge volume) a 405+FPU ASSP/CSSP like one company I've heard of or get the announced 440EP (that has the FPU macro cell).

-Matt

10x Juergen,

I'm asking because I have QNX (6.2.1a) running on this baby and it's extreamly slow with floating point stuff, so I was wondering if anyone could help me check the performance on linux ( I'm trying to convice our client to switch to linux )...

I'm also dissapointed of the integer performance too... On a StrongARM 1110 (

206MHz ) with linux the integer ops are 50% faster and the floating point is 150 TIMES faster!!!

Is anyone willing to run this test on PPC405 with linux (it's very simple. I'll send you the source.)?

Best Regards,

--
Alexander Popov                  ProSyst Bulgaria Inc.
RTOS Leader                      48 Vladajska Str.

send you the

Ok. Send me the code. I need some stress test...

--
Juergen Beisert        email: jbeisert _AT_ eurodsn _DOT_ de
EuroDesign embedded technologies GmbH  http://www.eurodsn.de