Bug ID: 199033
           Summary: Error with real time clock since upgrading to kernel
                    4.13 (/dev/rtc0 not found)
           Product: ACPI
           Version: 2.5
    Kernel Version: 4.13
          Hardware: Intel
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: BIOS
        Regression: No

Created attachment 274591
ACPI tables from acpidump

Since upgrading to kernel 4.13 (Ubuntu 17.10) the real time clock no longer
initializes. This has been verified in latest RC versions of the upstream

1) Boot kernel 4.13 or later

2)Here is output from 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

3)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

4)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.

Linux haven 4.13.0-36-generic #40-Ubuntu SMP Fri Feb 16 20:07:48 UTC 2018
x86_64 x86_64 x86_64 GNU/Linux

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

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)

A bug was filed with the RTC kernel developers who confirmed that this was
related to the wdat_wdt driver which is requesting ports 0x70-0x71 exclusively.
So, when the RTC driver tries to request the same
ports 0x70-0x77, it fails with -EBUSY.

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