setting up hibernation in arch linux

If you have just installed a basic window manager on your arch setup, it is highly likely that hibernation is not set up on your system. I hibernate my system very often and therefore, it is one of the first things that I set up on my system. This is a guide that I have prepared by stealing simplifying instructions from this archwiki page.

set up a swap file (or partition)

I recommend using a swap file. Although there exists much debate about the performance difference of using a swap partition vs. swap file, for a regular user the difference is unnoticeable and one added benefit of using a swapfile is that you can easily move a swap file around, delete old ones and create new ones (with a different size) at ease. The last feature is helpful when you have changed your RAM capacity. If you are looking for instructions to set up hibernation using a swap partition (instead of a swapfile), you can find many guides online.

Here I list instructions to create and setup a swap file:

• Create a swap file

  Use the dd tool for this purpose. (You can use tools like fallocate too)

    sudo dd if=/dev/zero of=/swapfile bs=1M count=16384
  

  Here I created a file of size 16GB that I shall use as a swapfile. It is recommended to have a swapfile which is equal (or 1.5 times) in size to your RAM amount. You can also place the swapfile in your home directory, I have mine at /home/pritom/swapfile.

• set appropriate permissions

  Swapfile must have specific permissions on, or else you can’t use it as swap.

    sudo chmod 600 /swapfile
  

• enable swapfile (temporary)

  You can enable and start using your newly created swapfile using the following commands:

    # set up the file as swap
    sudo mkswap /swapfile
  
    # enable file for swapping
    sudo swapon /swapfile
  

• updating fstab

  In order to make sure that the swapfile is enabled at reboot, we need to add an entry for it in the fstab file

  Assuming you already have a working fstab file, add the following line. Also note that if you already have a similar line for swap in it, remove the line.

    /swapfile 			none		swap      	defaults  	0 0
  

  • The first field is for the device, we add the path to the file here. If you were using a partition then you would add the mount point or the UUID of the device.
  • The second field is mount point, it is none in our case.
  • The third field is file system type, it is swap.
  • The fourth field is for mount options, we can set it as defaults
  • The fifth field is for backup operation, leave it as 0 for no backup
  • The sixth field is for file system check order, we don’t want fsck to check it so we leave it as 0.

gathering UUID and file offset values

You can find the swap device UUID using the command:

findmnt -no UUID -T /swapfile

In order to find the value of swap_file_offset, you need to run the following commands on your system.

filefrag -v /swapfile | awk '$1=="0:" {print substr($4, 1, length($4)-2)}'

Or,

you can install the uswsusp package and run swap-offset /swapfile.

editing grub config file

Edit the file at /etc/default/grub, preferably using sudoedit

sudoedit /etc/default/grub

Find the line that contains GRUB_CMDLINE_LINUX_DEFAULT and add the following options after it: (or if GRUB_CMDLINE_LINUX exists then add the following options to it)

GRUB_CMDLINE_LINUX="resume=UUID=<swap_device UUID> resume_offset=<swap_file_offset>"
# or you can edit `GRUB_CMDLINE_LINUX_DEFAULT`

Then, run sudo update-grub to update the grub config file.

add resume option to the list of hooks

Edit the file /etc/mkinitcpio.conf and add resume to the list of hooks.

# notice that resume is now added to the list of hooks
HOOKS=(base udev resume autodetect modconf block filesystems keyboard fsck)
#                   ^

Create a new image with the new config file by running sudo mkinitcpio -p

reboot your system

After rebooting you can test if your swapfile is working by running swapon -s. If you see a line that starts with /swapfile then it is working.

Test the hibernation by running systemctl hibernate.

If everything went well, your system should hibernate and resume successfully.

[optional] storing your swapfile in /home

If your swapfile is located in your /home directory (like in /home/pritom/swapfiile), you may not be able to use it for hibernation unless you make the following changes to turn off sandboxing option for \home directory.

run systemctl edit systemd-logind and add the following in the file that is opened:

[Service]
ProtectHome=read-only

I found this workaround here.