8.1-PRERELEASE: CPU packages not detected correctly

Andriy Gapon avg at freebsd.org
Tue Sep 21 17:52:34 UTC 2010

on 02/09/2010 11:25 Andriy Gapon said the following:
> on 01/09/2010 21:26 Jung-uk Kim said the following:
>> On Friday 27 August 2010 03:36 pm, Jung-uk Kim wrote:
>>> [3] AMD is working on an SMT-capable CPU (code-named Bulldozer) and
>>> my patch won't work on them.  If anyone has a Bulldozer sample,
>>> please look into it.
>> I checked AMD website today and found out a new CPUID Spec. Rev. 2.34 
>> was just released:
>> http://support.amd.com/us/Embedded_TechDocs/25481.pdf
>> They have added CPUID 0x8000001d and 0x8000001e to detect topology, it 
>> seems.  Also, CPUID 0x80000001 %ecx bit 22 (TopologyExtensions) tells 
>> you whether the above CPUID functions are supported.
>> Interesting...
> Yeah, I've heard that they are adding SMT capabilities in "Bulldozer"
> processors, so I guess they have to change CPU topology detection indicators.

The above comment by me is almost nonsense :)
I looked at the document with better attention and I think that what the new way
does is better/provides proper support for discovering non-uniform topologies
based on APIC IDs of the cores.

BTW, I am reading that AMD Bulldozer CPU package will consist of modules, which in
turn will consist of cores.  When a "core" would be something in between current
notion of core and current notion of hardware thread (SMT/HTT/whatever).
The Bulldozer cores will have independent arithmetic units and L1 caches, but
shared FPU, L2, fetch+decode and some other elements; L3 cache is per package
(shared by all "modules").

Andriy Gapon

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