[Bug 1987541] Update Released

[Łukasz Zemczak]

The verification of the Stable Release Update for shim has completed
successfully and the package is now being released to -updates.
Subsequently, the Ubuntu Stable Release Updates Team is being
unsubscribed and will not receive messages about this bug report.  In
the event that you encounter a regression using the package from
-updates please report a new bug using ubuntu-bug and tag the bug report
regression-update so we can easily find any regressions.

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https://bugs.launchpad.net/bugs/1987541

Title:
  shim executes GRUB w/ dirty instruction cache on arm64

Status in shim package in Ubuntu:
  Fix Released
Status in shim source package in Bionic:
  Fix Committed
Status in shim source package in Focal:
  Fix Committed
Status in shim source package in Jammy:
  Fix Committed
Status in shim source package in Kinetic:
  Fix Released

Bug description:
  [Impact]
  On arm64 platforms, GRUB may occasionally crash after being executed by shim. We're seeing it on the order of 1/100 boots.

  [Test Case]
  Put an arm64 server in a reboot loop. We're seeing this w/ a Cortex A72-based system (Nvidia Bluefield).

  [Fix]
  https://github.com/rhboot/shim/commit/5c537b3d0cf8c393dad2e61d49aade68f3af1401

  [What could go wrong]
  The only negative here would seem to be the performance impact of flushing the cache, which is unlikely to be noticeable.

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