[Bug 1873489] Re: lscpu cache information is incorrect with focal on arm 64-bit platform (ThunderX2)

[Taihsiang Ho]

Hi Mauricio, thank you for providing the information that I was not
aware of. It's very clear and helpful for me.

Because the ThunderX2 is unavailable for me currently, I verified the
output format with Focal on an arm d06 cpu, which is able to reproduce
the "issue" (my own host name "scobee"). It is exactly what you have
said.

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Title:
  lscpu cache information is incorrect with focal on arm 64-bit platform
  (ThunderX2)

Status in util-linux package in Ubuntu:
  Invalid

Bug description:
  Platform: Cavium Sabre Marvell ThunderX2

  The L1/L2/L3 cache output by "lscpu" is incorrect, and differes from
  the output with bionic.

  [Steps to Reproduce]
  1. Install ubuntu server (focal) on Sabre
  2. lspci

  [Expected Result]
  L1d cache:           32K
  L1i cache:           32K
  L2 cache:            256K
  L3 cache:            32768K

  [Actual Result]
  L1d cache:                       1.8 MiB                                                                              
  L1i cache:                       1.8 MiB                                                                              
  L2 cache:                        14 MiB                                                                               
  L3 cache:                        64 MiB    

  
  [More Information]
  1. eoan could reproduce this issue.
  2. bionic-hwe could not reproduce this issue (5.3.0-46-generic #38~18.04.1-Ubuntu)
  3. with focal, check the cpu cache directly from the virtual devices and the cache information looks good:
      $ cat /sys/devices/system/cpu/cpu0/cache/index0/level /sys/devices/system/cpu/cpu0/cache/index0/size
      1
      32K
  4. More information about the system which could reproduce the issue:

  
      ubuntu at apollo:~$ cat /sys/devices/system/cpu/cpu0/cache/index0/level /sys/devices/system/cpu/cpu0/cache/index0/size
      1
      32K
      ubuntu at apollo:~$ uname -a
      Linux apollo 5.4.0-24-generic #28-Ubuntu SMP Thu Apr 9 22:17:51 UTC 2020 aarch64 aarch64 aarch64 GNU/Linux
      ubuntu at apollo:~$ lsb_release -a
      No LSB modules are available.
      Distributor ID: Ubuntu
      Description:    Ubuntu Focal Fossa (development branch)
      Release:        20.04
      Codename:       focal
      ubuntu at apollo:~$ dpkg -l util-linux
      Desired=Unknown/Install/Remove/Purge/Hold
      | Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
      |/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
      ||/ Name           Version         Architecture Description
      +++-==============-===============-============-=================================
      ii  util-linux     2.34-0.1ubuntu9 arm64        miscellaneous system utilities
      ubuntu at apollo:~$

  ProblemType: Bug
  DistroRelease: Ubuntu 20.04
  Package: util-linux 2.34-0.1ubuntu9
  ProcVersionSignature: User Name 5.4.0-24.28-generic 5.4.30
  Uname: Linux 5.4.0-24-generic aarch64
  ApportVersion: 2.20.11-0ubuntu26
  Architecture: arm64
  CasperMD5CheckResult: skip
  Date: Fri Apr 17 16:00:13 2020
  SourcePackage: util-linux
  UpgradeStatus: No upgrade log present (probably fresh install)

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