group.of.nepali.translators team mailing list archive

[Andrea Righi <1918590@xxxxxxxxxxxxxxxxxx>]

Public bug reported:

[Impact]

In 1913739 we applied a fix to properly detect the right amount of cores
in AWS large instance types (> 255). However, this fix seems to work
properly only with kernels > 4.4. Even if it doesn't seem to introduce
any failure or regression, it is probably just safer to revert this
commit in the Xenial kernel, and keep it on the other kernels (> 4.4).

[Test plan]

Boot an instance type with > 255 cpus and check the amount of cores
detected.

[Fix]

Revert commit:
 561ef22a7d396289a1c5a1d18057ccdf9bb59826 ("iommu/vt-d: Gracefully handle DMAR units with no supported address widths")

[Regression potential]

Reverting the commit simply restores the old behavior, so we won't be
able to detect the right amount of CPUs in large instances, but we are
sure that we won't also introduce any potential failure or regressions
by restoring the previous behavior. And this is affecting only the
Xenial kernel, that is approaching to EOL.

** Affects: linux-aws (Ubuntu)
     Importance: Undecided
         Status: New

** Affects: linux-aws (Ubuntu Xenial)
     Importance: Undecided
         Status: New

** Also affects: linux-aws (Ubuntu Xenial)
   Importance: Undecided
       Status: New

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https://bugs.launchpad.net/bugs/1918590

Title:
  aws: revert change to support instance types > 255 cpu cores in xenial

Status in linux-aws package in Ubuntu:
  New
Status in linux-aws source package in Xenial:
  New

Bug description:
  [Impact]

  In 1913739 we applied a fix to properly detect the right amount of
  cores in AWS large instance types (> 255). However, this fix seems to
  work properly only with kernels > 4.4. Even if it doesn't seem to
  introduce any failure or regression, it is probably just safer to
  revert this commit in the Xenial kernel, and keep it on the other
  kernels (> 4.4).

  [Test plan]

  Boot an instance type with > 255 cpus and check the amount of cores
  detected.

  [Fix]

  Revert commit:
   561ef22a7d396289a1c5a1d18057ccdf9bb59826 ("iommu/vt-d: Gracefully handle DMAR units with no supported address widths")

  [Regression potential]

  Reverting the commit simply restores the old behavior, so we won't be
  able to detect the right amount of CPUs in large instances, but we are
  sure that we won't also introduce any potential failure or regressions
  by restoring the previous behavior. And this is affecting only the
  Xenial kernel, that is approaching to EOL.

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