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[Peter Milley <1743027@xxxxxxxxxxxxxxxxxx>]

Public bug reported:

(originally asked over at askubuntu.com, but is still unresolved:
https://askubuntu.com/questions/971349/problem-with-real-time-clock-
since-upgrading-to-ubuntu-17-10)

I recently upgraded from Ubuntu 17.04 to Ubuntu 17.10 using the software
update process. The update completed without any errors, and Ubuntu
17.10 is now running without any major issues.

However, I was running a script previously that uses rtcwake which has
since stopped working. The script automatically hibernates my laptop
after a set period of time in sleep mode, and was working perfectly in
Ubuntu 17.04.

In the process of troubleshooting, I discovered that the problem was
with rtcwake which is complaining about /dev/rtc0 missing.

Here is output from a sample rtcwake command:

peter@haven:~$ rtcwake -m no -s 1300
rtcwake: assuming RTC uses UTC ...
rtcwake: /dev/rtc0: unable to find device: No such file or directory

I verified that in fact, that directory is missing. Since this was
working prior to the upgrade, I have to assume that it was there
previously, but I don't know for sure.

In researching the error, I found some suggestions to get further
information with timedatectl and hwclock, so here are the results from
those commands as well.

Output of timedatectl:

peter@haven:~$ timedatectl
      Local time: Fri 2017-10-27 19:06:26 EDT
  Universal time: Fri 2017-10-27 23:06:26 UTC
        RTC time: n/a
       Time zone: America/New_York (EDT, -0400)
 Network time on: yes
NTP synchronized: yes
 RTC in local TZ: no

Output of hwclock --debug:

peter@haven:~$ sudo hwclock --debug
[sudo] password for peter: 
hwclock from util-linux 2.30.1
Trying to open: /dev/rtc0
Trying to open: /dev/rtc
Trying to open: /dev/misc/rtc
No usable clock interface found.
hwclock: Cannot access the Hardware Clock via any known method.

UPDATE

When I boot with my old kernel, 4.10.0-37-generic the real-time clock
works fine.

I get the following RTC messages in dmesg when I boot the
4.13.0-16-generic kernel:

peter@haven:~$ dmesg | grep -i rtc
[    0.089393] RTC time: 17:03:55, date: 11/01/17
[    1.238784] rtc_cmos 00:01: RTC can wake from S4
[    1.238794] rtc_cmos: probe of 00:01 failed with error -16
[    1.295459] hctosys: unable to open rtc device (rtc0)

UPDATE #2

Well, I was starting to believe that I had a hardware issue, since
discovering I was unable to save changes to my BIOS and could not boot
from USB. As it turns out, my laptop was bitten by this bug:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1734147 causing my
BIOS to be locked in a read-only state.

Once I resolved the BIOS issue, and fixed the USB boot problem, I did a
live boot of Ubuntu 17.10. The issue with my real time clock still
exists under this clean boot scenario, yet when I boot other distros,
like Linux Mint 18.3 and the real time clock works fine. I feel this
definitely has something to do with the Ubuntu install, perhaps even a
kernel bug.

UPDATE #3

More evidence to suggest this is a kernel bug: I live-booted a copy of
Antergos Linux, which was using the Arch kernel 4.14.12-1-ARCH and it
exhibited the same problem with the real time clock as Ubuntu 17.10. In
addition, I confirmed that the Linux Mint version I booted earlier (see
Update #2) was on the Ubuntu kernel 4.10.0-38-generic.

So, I suspect that sometime between kernels 4.10 and 4.13 this bug was
introduced.

** Affects: compiz-plugins-main (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1743027

Title:
  error loading realtime clock since upgrading to 17.10

Status in compiz-plugins-main package in Ubuntu:
  New

Bug description:
  (originally asked over at askubuntu.com, but is still unresolved:
  https://askubuntu.com/questions/971349/problem-with-real-time-clock-
  since-upgrading-to-ubuntu-17-10)

  I recently upgraded from Ubuntu 17.04 to Ubuntu 17.10 using the
  software update process. The update completed without any errors, and
  Ubuntu 17.10 is now running without any major issues.

  However, I was running a script previously that uses rtcwake which has
  since stopped working. The script automatically hibernates my laptop
  after a set period of time in sleep mode, and was working perfectly in
  Ubuntu 17.04.

  In the process of troubleshooting, I discovered that the problem was
  with rtcwake which is complaining about /dev/rtc0 missing.

  Here is output from a sample rtcwake command:

  peter@haven:~$ rtcwake -m no -s 1300
  rtcwake: assuming RTC uses UTC ...
  rtcwake: /dev/rtc0: unable to find device: No such file or directory

  I verified that in fact, that directory is missing. Since this was
  working prior to the upgrade, I have to assume that it was there
  previously, but I don't know for sure.

  In researching the error, I found some suggestions to get further
  information with timedatectl and hwclock, so here are the results from
  those commands as well.

  Output of timedatectl:

  peter@haven:~$ timedatectl
        Local time: Fri 2017-10-27 19:06:26 EDT
    Universal time: Fri 2017-10-27 23:06:26 UTC
          RTC time: n/a
         Time zone: America/New_York (EDT, -0400)
   Network time on: yes
  NTP synchronized: yes
   RTC in local TZ: no

  Output of hwclock --debug:

  peter@haven:~$ sudo hwclock --debug
  [sudo] password for peter: 
  hwclock from util-linux 2.30.1
  Trying to open: /dev/rtc0
  Trying to open: /dev/rtc
  Trying to open: /dev/misc/rtc
  No usable clock interface found.
  hwclock: Cannot access the Hardware Clock via any known method.

  UPDATE

  When I boot with my old kernel, 4.10.0-37-generic the real-time clock
  works fine.

  I get the following RTC messages in dmesg when I boot the
  4.13.0-16-generic kernel:

  peter@haven:~$ dmesg | grep -i rtc
  [    0.089393] RTC time: 17:03:55, date: 11/01/17
  [    1.238784] rtc_cmos 00:01: RTC can wake from S4
  [    1.238794] rtc_cmos: probe of 00:01 failed with error -16
  [    1.295459] hctosys: unable to open rtc device (rtc0)

  UPDATE #2

  Well, I was starting to believe that I had a hardware issue, since
  discovering I was unable to save changes to my BIOS and could not boot
  from USB. As it turns out, my laptop was bitten by this bug:
  https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1734147 causing
  my BIOS to be locked in a read-only state.

  Once I resolved the BIOS issue, and fixed the USB boot problem, I did
  a live boot of Ubuntu 17.10. The issue with my real time clock still
  exists under this clean boot scenario, yet when I boot other distros,
  like Linux Mint 18.3 and the real time clock works fine. I feel this
  definitely has something to do with the Ubuntu install, perhaps even a
  kernel bug.

  UPDATE #3

  More evidence to suggest this is a kernel bug: I live-booted a copy of
  Antergos Linux, which was using the Arch kernel 4.14.12-1-ARCH and it
  exhibited the same problem with the real time clock as Ubuntu 17.10.
  In addition, I confirmed that the Linux Mint version I booted earlier
  (see Update #2) was on the Ubuntu kernel 4.10.0-38-generic.

  So, I suspect that sometime between kernels 4.10 and 4.13 this bug was
  introduced.

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