[Cbe-oss-dev] Cell and new CPU feature bits

Andrew Pinski pinskia at physics.uc.edu
Fri May 19 15:27:17 EST 2006

On May 18, 2006, at 10:19 PM, Olof Johansson wrote:

>>  - Lack of data stream instructions. Until now, it was assumed that
>> those were tied to the presence
>>    of an Altivec (and they are documented in the Altivec manual).  
>> Maybe
>> we should split that to a
>>    new bit. I don't know if existing applications use them though, if
>> they do, there will be a
>>    problem to get them updated as the new bit isn't present on older
>> kernels...
> I'm assuming you mean the instructions described under "AltiVec Memory
> Bandwidth Management" in secion 5.2 of the Altivec PEM -- dst, dstt,
> dstst, dss and dssall?

They are nops on the Cell though.  They are also microcoded on the 970.
> If you're referring to the extended dcbt that includes streaming hints
> (as documented in the 64-bit PEM, but not in PPC book2 2.02), then a
> separate bit is likely needed -- obviously at least 970 seems to
> implement them.

Yes they are implemented on the 970.

Andrew Pinski

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