[Bug 1485086] Re: lshw does not display cpu information correctly on aarch64

[Raghuram Kota]

Hi Chris, 
Manoj verfieid this for Trusty and Vivid (comms #4,#5). Please let us know if there is anything you need from us to complete this SRU. 

Thanks,
Raghu

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Title:
  lshw does not display cpu information correctly on aarch64

Status in lshw package in Ubuntu:
  Fix Released
Status in lshw source package in Trusty:
  Fix Committed
Status in lshw source package in Vivid:
  Fix Committed
Status in lshw source package in Wily:
  Fix Released

Bug description:
  On certain aarch64 systems lshw does not display cpu information
  correctly. It displays cpu0 and the any subsequent cpus are displayed
  as DISABLED.  On a multi core aarch64 system lshw displays the
  following:

    *-core
         description: Motherboard
         physical id: 0
         capabilities: < Intentionally Removed >
       *-cpu:0
            description: CPU
            product: cpu
            physical id: 0
            bus info: cpu at 0
       *-cpu:1 DISABLED
            description: CPU
            product: cpu
            physical id: 2
            bus info: cpu at 1
       *-cpu:2 DISABLED
            description: CPU
            product: cpu
            physical id: 4
            bus info: cpu at 2
       *-cpu:3 DISABLED
            description: CPU
            product: cpu
            physical id: 5
            bus info: cpu at 3

  Please consider the attached merge proposal for SRU in trusty.

  [Impact]

   * When users run lshw on aarch64 systems the CPU information is not
  displayed correctly. It displays cpu0 and the any subsequent cpus are
  displayed as DISABLED. Please refer to bug description for details on
  output.

   * This bug can be fixed by adding code to handle the aarch64 case
  similar to the existing code for powerpc, x86, x64, ia64 etc. But,
  lshw upstream has done the work of adding support for s390 and
  aarch64. It will be better to backport those changes rather than using
  a bandaid fix for aarch64 in ubuntu.

  
  [Test Case]

   * On an ubuntu aarch64 system run the command sudo lshw and look at
  the information displayed for cpu. Without the patch you should see
  that CPU 1-N will be DISABLED.

   * With the patch run lshw on aarch64 ubuntu system and you should see
  that it lists CPUs 1-N and display information about the CPU.

  [Regression Potential]

   * Currently support for aarch64 is broken, so if a regression were to
  occur it could be in other archs. But, the changes introduced by this
  patch is to support aarch64 and s390 systems and those changes should
  not impact other archs.

   * This patch was tested on a 48 core aarch64 system running Trusty
  and found to work as expected. lshw package for wily and trusty were
  built and tested on an aarch64 system running Trusty.

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