[Xen-devel] Wrong number of sockets on IBM x3850 M2

[Gary Grebus <ggrebus@xxxxxxxxxxxxxxx>]

One of our customers has reported that Xen determines the wrong topology
for their machines, identifying them as 6 sockets x 4 cores when in fact
they are 4 sockets x 6 cores (Intel(R) Xeon(R) CPU X7460  @ 2.66GHz
stepping 01).  The systems are IBM x3850 M2.  

I don't have access to a machine, but from a log I suspect it has
something to do with the strange APIC ids that are reported:

(VMM) Booting processor 1/32 eip 8c000
...
(VMM) Booting processor 2/16 eip 8c000
...
(VMM) Booting processor 3/56 eip 8c000
(VMM) Booting processor 4/9 eip 8c000
(VMM) Booting processor 5/33 eip 8c000
(VMM) Booting processor 6/17 eip 8c000
(VMM) Booting processor 7/57 eip 8c000
(VMM) Booting processor 8/10 eip 8c000
(VMM) Booting processor 9/34 eip 8c000
(VMM) Booting processor 8/10 eip 8c000
(VMM) Booting processor 11/58 eip 8c000
(VMM) Booting processor 12/11 eip 8c000
(VMM) Booting processor 13/35 eip 8c000
(VMM) Booting processor 14/19 eip 8c000
(VMM) Booting processor 15/59 eip 8c000
(VMM) Booting processor 16/108 eip 8c000
(VMM) Booting processor 17/68 eip 8c000
(VMM) Booting processor 18/84 eip 8c000
(VMM) Booting processor 19/124 eip 8c000
(VMM) Booting processor 20/109 eip 8c000
(VMM) Booting processor 21/69 eip 8c000
(VMM) Booting processor 22/85 eip 8c000
(VMM) Booting processor 23/125 eip 8c000

phys_pkg_id() which is used in determining the topology appears to
always read an id value from an APIC register, but I see that recent
Linux kernels have much more elaborate logic in this area.

Has anyone else seen this or know a solution?

Thanks,
        /gary

-- 
Gary Grebus
Virtual Iron Software, Inc.



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