This bug is awaiting verification that the kernel in -proposed solves
the problem. Please test the kernel and update this bug with the
results. If the problem is solved, change the tag 'verification-needed-
bionic' to 'verification-done-bionic'. If the problem still exists,
change the tag 'verification-needed-bionic' to 'verification-failed-
bionic'.

If verification is not done by 5 working days from today, this fix will
be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how
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** Tags added: verification-needed-bionic

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https://bugs.launchpad.net/bugs/1528684

Title:
  Error parsing PCC subspaces from PCCT

Status in linux package in Ubuntu:
  Fix Committed
Status in linux source package in Bionic:
  Fix Committed

Bug description:
  [Impact]
  A scary-looking message appears in dmesg in several places during boot:

  "Error parsing PCC subspaces from PCCT"

  This could cause users to believe they have buggy firmware, in cases
  where it's actually fine.

  [Test Case]
  dmesg | grep "Error parsing PCC subspaces"

  [Fix]
  Resolved in upstream commit that cleanly cherry-picks back to bionic:
  8f8027c5f935 mailbox: PCC: erroneous error message when parsing ACPI PCCT

  [Regression Risk]
  PCC is a generic ACPI-defined mechanism for the OS and firmware to 
communicate. Since the fix does change how the tables are parsed, regression 
scenarios could include breakages in PCC clients (things that use this layer to 
communicate to firmware). The only Kconfig option I see in bionic's source that 
depends on CONFIG_PCC is the CPPC library, which provides ACPI CPU performance 
management used by the cppc-cpufreq driver and is used by the scaling 
driver/governor for Sandy bridge processors.

  Tested on an Nvidia DGX system. This is an upstream fix, so any
  regressions will have upstream support.

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