I'm running Debian10/KDE with kernel 4.19.0-5-amd64. I have 16GB of RAM, a swapfile of 25GB on my separate home partition (the partition that holds the OS is too small for it). My hard drive is fully encrypted and I don't have a separate graphics card or a special graphics driver. I'm booting from an SSD disk with UEFI.
The following doesn't apply anymore after upgrading to Debian 10 and applying the spectre-meltdown fix (intel-microcode):
When I try to hibernate it just turns off the screen for a second or so and then just locks the screen. When I log back in everything is as before (Firefox is still open) except that my WLAN got disconnected.
I think the relevant messages in /var/log/syslog are:
kernel: PM: Hibernation image created [...]
kernel: Suspended for 1.528 seconds
kernel: Enabling non-boot CPUs ...
kernel: x86: Booting SMP configuration:
kernel: smpboot: Booting Node 0 Processor 1 APIC 0x2
kernel: cache: parent cpu1 should not be sleeping
kernel: CPU1 is up
kernel: smpboot: Booting Node 0 Processor 2 APIC 0x4
kernel: cache: parent cpu2 should not be sleeping
kernel: CPU2 is up
kernel: smpboot: Booting Node 0 Processor 3 APIC 0x6
kernel: cache: parent cpu3 should not be sleeping
kernel: CPU3 is up
kernel: ACPI: Waking up from system sleep state S4
kernel: PM: noirq thaw of devices complete after 19.232 msecs
kernel: PM: early thaw of devices complete after 16.070 msecs
kernel: parport_pc 00:01: activated
kernel: serial 00:04: activated
kernel: rtc_cmos 00:07: System wakeup disabled by ACPI
sudo swapon --show tells me the swapfile is activated. I already ran
sudo sh -c "echo XHC > /proc/acpi/wakeup" so that /proc/acpi/wakeup only has disabled entries now except for one that changes back to enabled and I changed all the textfiles to disabled that were shown when running
grep enabled /sys/bus/usb/devices/*/power/wakeup.
I also tried it with uswsusp as described in https://wiki.debian.org/Hibernation/Hibernate_Without_Swap_Partition (and https://askubuntu.com/q/6769) but when I run
sudo s2disk to test it it tries to hibernate but when I start it again it just boots again. So I guess I would need to do even further configuration to get hibernation working with uswsusp due to my disk encryption. But I'm not exactly sure what needs to be done and I don't want to wreck my hard drive - for example I don't know whether I should put in
resume device = /dev/mapper/sda2_crypt or
resume device = name--vg-home in uswsusp.conf as the home partition that holds the swapfile is
name--vg-home. Or whether it needs an offset for the location of the swapfile. And mainly I would like to use native hibernation as it was apparently intended by Debian instead of uswsusp. If it would only work with uswsusp why isn't that built into the native hibernation?
Update: After upgrading to Debian10 and the latest kernel it also just does a normal reboot after pressing the Hibernate button. In syslog it says:
systemd: Reached target Sleep.
systemd: Starting Hibernate...
kernel: PM: Image not found (code -22)
systemd-tmpfiles: [/usr/lib/tmpfiles.d/speech-dispatcher.conf:1] Line references path below legacy directory /var/run/, updating /var/run/speech-dispatcher → /run/speech-dispatcher; please update the tmpfiles.d/ drop-in file accordingly.
Likely I have to apply the changes described under "Tricks when the system is fully encrypted" of the wiki-page. But I don't have a /etc/uswsusp.conf file.
During Debian installation I removed the swap partition and set up a volume group which always had some problems (I installed multiple times) as some error messages keep showing when booting before I'm prompted to enter the password to decrypt my disk.
WARNING: Failed to connect to lvmetad. Falling back to device scanning. Volume group "name-vg" not found. Cannot process volume group name-vg Please unlock sda2_crypt:. But I guess that's a separate issue/question.)
I'm trying to get hibernation working because I'd like to save some energy and because roughly every 10th wakeup from suspend just goes to a black screen with the keyboard not working (note: I haven't had any of these after upgrade I will update this if that changes). I found that people have that same issue but couldn't find a solution so far. Here it was recommended to create a swapfile. At first I only followed these exact steps with the only exception being that my swapfile is located on my home partition and not in the root folder. But that didn't work as I'm still getting black screens.