Re: [gentoo-amd64] Upgrade from single to dual core CPU

[Marco Matthies]

Matthias Wolle wrote:
> "The Athlon 64 X2 masquerade as hyperthreading capable to benfit from
> hyperthreading optimizations."

Intel processors will indicate Hyperthreading capability in bit 28 of 
edx and number of logical processors in bits 16-23 of ebx after issuing 
the cpuid instruction. [1][2]

According to [3], athlon x2 will do this as well (set edx[2]=1 and 
indicate two logical processors) to ensure easier software transition 
(maybe windows, games, etc.?). Another source [4] (in german only, 
sorry), indicates there is another bit set after cpuid to indicate if 
the processor is really hyperthreading capable or only faking it. 
Additionally, they are able to indicate the number of physical 
processors as well through cpuid.

Unfortunately, I do not have a x2, so i cannot confirm this... anyone 
here have more info?

Marco

[1] 
http://www.intel.com/cd/ids/developer/asmo-na/eng/dc/threading/knowledgebase/43843.htm
[2] 
http://intel.com/cd/ids/developer/asmo-na/eng/dc/threading/211924.htm?page=5
[3] http://www.x86-secret.com/?option=newsd&nid=870
[4] http://www.tecchannel.de/server/hardware/402399/index13.html
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