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** Changed in: linux (Ubuntu)
       Status: New => Confirmed

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  Significantly lower power and thermal limits on ThinkPad T480s (and
  probably others) than on Windows

Status in linux package in Ubuntu:

Bug description:
  A ThinkPad T480s under windows has a power limit of 44W, both short
  and long term, with a thermal maximum of about 93C or so. Under Linux,
  the power limits are 44W and 15W (short) or so, and the thermal limit
  is 80C, causing a significant performance loss.

  Looking at MSR and MCHBAR values, we can see that the values are
  correctly at 44W in the MSR, but the MCHBAR is set to a lower value:

  $ sudo rdmsr -a 0x610
  $ sudo /home/jak/Downloads/iotools-1.5/iotools mmio_read64 0xfed159a0

  Setting the MCHBAR to the same value as the MSR register solves the problem. 
At some point intel-rapl seems to reduce overall frequency to 600 MHz, though.

  The thermal limit is configured in MSR register 0x1a2; rdmsr -f 29:24
  -d 0x1a2 returns 20. Setting those bits to 7 increases it, resulting
  in performance comparative to Windows.

  Most of the analysis is based on the analysis in

  This applies to all bionic kernels I have tested so far, including

  Ubuntu 4.15.0-13.14-generic 4.15.10
  ApportVersion: 2.20.9-0ubuntu4
  Architecture: amd64
   /dev/snd/pcmC2D0p:   jak        5881 F...m pulseaudio
   /dev/snd/controlC2:  jak        5881 F.... pulseaudio
   /dev/snd/controlC1:  jak        5881 F.... pulseaudio
   /dev/snd/controlC0:  jak        5881 F.... pulseaudio
  CurrentDesktop: GNOME
  DistroRelease: Ubuntu 18.04
  InstallationDate: Installed on 2018-03-14 (28 days ago)
  InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Alpha amd64 (20180313)
  MachineType: LENOVO 20L8S02D00
  Package: linux (not installed)
  ProcFB: 0 inteldrmfb
  ProcKernelCmdLine: root=/dev/mapper/ubuntu--vg-root ro rootflags=subvol=@ 
quiet splash vt.handoff=1
  ProcVersionSignature: Ubuntu 4.15.0-13.14-generic 4.15.10
   linux-restricted-modules-4.15.0-13-generic N/A
   linux-backports-modules-4.15.0-13-generic  N/A
   linux-firmware                             1.173
  Tags:  bionic
  Uname: Linux 4.15.0-13-generic x86_64
  UpgradeStatus: No upgrade log present (probably fresh install)
  UserGroups: adm cdrom dip kvm lpadmin lxd plugdev sambashare sudo
  _MarkForUpload: True 01/22/2018
  dmi.bios.vendor: LENOVO
  dmi.bios.version: N22ET31W (1.08 )
  dmi.board.asset.tag: Not Available 20L8S02D00
  dmi.board.vendor: LENOVO
  dmi.board.version: Not Defined
  dmi.chassis.asset.tag: No Asset Information
  dmi.chassis.type: 10
  dmi.chassis.vendor: LENOVO
  dmi.chassis.version: None
dmi:bvnLENOVO:bvrN22ET31W(1.08):bd01/22/2018:svnLENOVO:pn20L8S02D00:pvrThinkPadT480s:rvnLENOVO:rn20L8S02D00:rvrNotDefined:cvnLENOVO:ct10:cvrNone: ThinkPad T480s 20L8S02D00
  dmi.product.version: ThinkPad T480s
  dmi.sys.vendor: LENOVO

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