Comment 43 for bug 1774950

@cmeerw - It took me a while to realise that getting hibernate to work on 18.04 required adding the kernel parameter 'resume=UUID=uuidofswappartition' (and also 'resume_offset=' if you're using a swap file) to /etc/default/grub.

(Ubuntu 16.04 and Kubuntu 16.04 will hibernate happily without the 'resume=' parameter added, so I was starting to wonder if hibernate was working on any machine after 16.04!)

Tested using `sudo systemctl hibernate` on the HP Pavilion N3540 with suspend issues. The results are the same for both Ubuntu and Kubuntu 18.04.

kernel 4.14.47

- Hibernate function works as it should

kernel 4.15.0-24 (with patch applied)

- Hibernate begins as normal but system does not shut down by itself. PowerLED stays on. Machine unresponsive. Holding down the power button to force shutdown is required.

- Upon reboot, the system resumes from where it left off, as if hibernate had worked fine.

--kern.log entries look the same irrespective of whether the system hangs and requires forced shutdown.

 PM: hibernation entry
 PM: Syncing filesystems ...
- (timestamp gap of about a minute before next entries - shutdown then reboot) -
 PM: done.
 Freezing user space processes ... (elapsed 0.001 seconds) done.
 OOM killer disabled.
 PM: Marking nosave pages: [mem 0x00000000-0x00000fff]
etc...

So hibernate almost works as it should but requires a forced shutdown in the 4.15.0-24 kernel with the patch applied.

(Also tested a machine that doesn't experience suspend issues and hibernate works as it should with standard up-to-date Ubuntu 18.04 with kernel 4.15.0-23)