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  1. XenServer Org
  2. XSO-635

Wrong CPU Cores detection on Skylake processors



    • Bug
    • Resolution: Done
    • Blocker
    • None
    • 6.5 SP1, 7.0, Ely alpha, 7.1, 7.2
    • API, other
    • None
    • Mobo: Intel S1200SP
      Processor: Intel(R) Xeon(R) CPU E3-1230 v5 @ 3.40GHz
      Ram: 8GB
      Disk: 1TB (No RAID)
      SO: Xenserver 7


      I've been having this issue only with this processor/chipset. I can install XenServer, but when it boots doesn't recognize all the cores that it should be. The processor has 4 Physycal CPUs and it has Hyperthreading enabled on the BIOS (VT-d and VT-x also are activated), so it has 8 logical cores. Once installed /proc/cpuinfo shows 4 cores, and xl info show only one. In XenCenter, shows only one CPU available, and it generates the imposibility to give more than one core to a VM. There is a post on the forum that explains and gives more info of the problem: http://discussions.citrix.com/topic/381364-xen-detects-only-one-cpu/

      I'm referring this here because it's a very big issue for us, basically we cannot use Xenserver on this hardware, and it seems to be related to the Xen Kernel, but i cannot find any solution, and in the forum, i couldn't find any help. Bear in mind that almost all the hardware available right now belongs to the "Skylake" family, so this issue is a real blocker . I've tested this on 6.5 & 7 and it's the same, also another person tried it on "Ely" and doesn't seems to be solved.


        1. dmesg.txt
          55 kB
        2. dmesg-debian
          182 kB
        3. dmesg-debian
          82 kB
        4. hypervisor.log
          27 kB
        5. hypervisor.log
          15 kB
        6. putty.log
          29 kB
        7. xensource.log
          262 kB
        8. xen-xso-635-v1.gz
          995 kB
        9. xl-dmesg.log
          27 kB



            SimonCro Simon Crowe
            gperez.tlp gperez.tlp
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