'sudo hwclock -s' fails with 'settimeofday() failed: Invalid argument'

Rik, thanks for reporting this bug.
You're right, it's a regression in hwclock between glibc 2.30/2.31.
It's fixed in util-linux upstream; preparing a debdiff for Focal.

...

$ lsb_release -cs
focal

Older glibc:
---

$ dpkg -s util-linux libc6 | grep ^Version:
Version: 2.34-0.1ubuntu8
Version: 2.30-0ubuntu3

$ sudo hwclock -s
$ echo $?
0

Newer glibc:
---

$ sudo apt install libc6
.
The following packages will be upgraded:
  libc-bin libc-dev-bin libc6 libc6-dev locales
.

$ dpkg -s util-linux libc6 | grep ^Version:
Version: 2.34-0.1ubuntu8
Version: 2.31-0ubuntu6

$ sudo hwclock -s
hwclock: settimeofday() failed: Invalid argument
$ echo $?
1

Upstream:
---

This is fixed with this upstream commit.
Preparing a debdiff for Focal.

ubuntu@focal:~/util-linux$ sudo ./hwclock -s
$ echo $?
0

commit cd781c405be82540484da3bfe3d3f17a39b8eb5c
Author: J William Piggott <email address hidden>
Date: Fri Feb 21 20:03:47 2020 -0500

    hwclock: make glibc 2.31 compatible

The patched package built correctly on all architectures on PPA [1].

And now 'hwclock -s' works again.

$ dpkg -s util-linux libc6 | grep ^Version:
Version: 2.34-0.1ubuntu9
Version: 2.31-0ubuntu6

$ sudo hwclock -s
$ echo $?
0

Attaching debdiff, and asking for sponsorship.

[1] https://launchpad.net/~mfo/+archive/ubuntu/lp1870316

Thanks, uploaded to focal now

The only autopkgtest 'regression' is openjdk-8/8u252-b07-1/armhf,
which is a flaky test. Triggering a re-run. Error in test logs:

> jdk FLAKY timed out

This bug was fixed in the package util-linux - 2.34-0.1ubuntu9

---------------
util-linux (2.34-0.1ubuntu9) focal; urgency=medium

  * d/p/hwclock-make-glibc-2.31-compatible.patch: fix hwclock
    for settimeofday(2) changes in glibc 2.31. (LP: #1870316)

 -- Mauricio Faria de Oliveira <email address hidden> Thu, 02 Apr 2020 12:29:40 -0300