[Bug 1991898] Re: [FFe] 2.36-0ubuntu4 update (various bugfixes + ARC enablement)

[Michael Hudson-Doyle]

On Sat, 8 Oct 2022 at 07:00, Steve Langasek <1991898 at bugs.launchpad.net>
wrote:

> > While we could assume that users have up-to-date microcode on a running
> > system, this issue could manifest when trying to install Ubuntu on a
> fresh
> > computer *before* the user had a chance to update the microcode.
>
> This doesn't block acceptance of the upload, but microcode updates are
> supposed to be applied to the CPU from early boot by the kernel via the
> initramfs, including in install images; so why is this a concern in
> practice?
>

I think the more realistic scenario is a 22.10 container on an OS that does
not mandate microcode updates. Also I don't know if all processors that are
affected by this will get the relevant instructions enabled by an
up-to-date microcode (I haven't even looked into this at all though).

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https://bugs.launchpad.net/bugs/1991898

Title:
  [FFe] 2.36-0ubuntu4 update (various bugfixes + ARC enablement)

Status in glibc package in Ubuntu:
  Triaged

Bug description:
  Hi,

  We'd like to upload a new glibc to Kinetic.
  It ships a fix for https://bugs.launchpad.net/ubuntu/+source/glibc/+bug/1991652 as well as multiple patches from the upstream stable release branch, for the following bugs:

  https://sourceware.org/bugzilla/show_bug.cgi?id=28937
  Dynamic loader issue

  https://sourceware.org/bugzilla/show_bug.cgi?id=29583
  iconv issue on 32-bit architectures with large files. Might impact armhf.

  https://sourceware.org/bugzilla/show_bug.cgi?id=29611
  Potentially incorrect use of BMI instructions on AVX2 optimised routines

  https://sourceware.org/bugzilla/show_bug.cgi?id=29607
  https://sourceware.org/bugzilla/show_bug.cgi?id=29605
  Couple of nscd regressions

  https://sourceware.org/bugzilla/show_bug.cgi?id=29638
  arc4random issue on older kernels (including the Trusty ones)

  I believe the BMI issue is particularly important to fix. While most
  hardware has both BMI and AVX2, there are still some without BMI
  support, or even some that only gained BMI support via microcode
  updates. While we could assume that users have up-to-date microcode on
  a running system, this issue could manifest when trying to install
  Ubuntu on a fresh computer *before* the user had a chance to update
  the microcode.

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