What defines a cpu table platform? (was Re: Change 440GP platform to ppc440)

[Kumar Gala]

On May 1, 2007, at 10:38 PM, Kumar Gala wrote:

>
> On Apr 24, 2007, at 12:46 AM, Stefan Roese wrote:
>
>> On Tuesday 24 April 2007 02:12, Roland Dreier wrote:
>>>>> I recall dimly that there was some user-visible difference
>>>>> between the
>>>>> 440GP and the other 440 processors, and that's why we made the
>>>>> platform string different.  I don't recall what the difference  
>>>>> was.
>>>
>>> FWIW, I've run the same userspace (binaries) on 405GPr, 440GP and
>>> 440SPe without any problems.  Not that I'm a 4xx expert by any
>>> stretch, but I don't know of anything special about the 440GP.
>>
>> I don't know of any differences either. So I'm voting to change the
>> platform
>> to ppc440 too.
>
> After some discussion with Paul we think we figured out why 440GP was
> marked differently.  I doesn't implement 'isel', and all other  
> 440's do.

This whole discussion makes me wondering what defines a new cpu table  
platform?  I know one application of this value is for being able to  
pick "platform" specific/tuned libraries.  Are there other uses?

If its just for libraries wouldn't the existence of FPUs and SPE/ 
Altivec warrant different platform types?

- k