Hello Wei Lin,

The x86 indeed needs regular updates to support latest processors. But this x86 backend is mostly only useful if you're using an operating system that does not export topology information. If you're using Linux, a recent kernel should already tell hwloc everything you need, and the x86 backend will not be used at all. Do you actually see some wrong lstopo output on such machines? FWIW, we use hwloc on many Westmere-EP and Nehalem-EX machines without problem, and we know SGI has been using it on large UV machines too.

Best regards,

Le 01/12/2010 10:07, Wei Lin a écrit :

Hi, hwloc-devel


     I cannot find the code branch from “src/topology-x86.c “which can support for 32-bit APIC ID and CPUID leaf 0xb of Intel’s new processors.  

So I think current hwLoc cannot support for latest Intel CPU with x2APIC.


Linux kernel 2.6.30 or following version already supports this hardware feature

and uses CPUID leaf 0xb to recognize the topology for more than 1024 logical processors in SGI’s super computer.


I think hwloc could also support this.


The following docs from Intel give details about x2APIC:



   or <<Intel® 64 Architecture Processor Topology Enumeration>>



Wei Lin



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