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
Linux kernel 2.6.30 or following version already supports this hardware
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(r) 64 Architecture Processor Topology Enumeration>>