Arch Linux Hibernation Using Swap File

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In most cases, we generally use Swap File for easier adjustment and configuration flexibility.

References: Arch Wiki, Arch Wiki, Arch BBS

Creating Swap File (Reference: Arch Wiki)

Manual Method

Creating the Swap File

Use the root account and the fallocate command to create a swap file of the desired size (M = Mebibytes, G = Gibibytes). For example, create a 16G swap file (for hibernation, it’s best to set it to your computer’s RAM size):

# fallocate -l 16G /swapfile

Note: The fallocate command may cause issues on F2FS or XFS filesystems. [1] As an alternative, use the dd command, though it’s slower:

# dd if=/dev/zero of=/swapfile bs=1M count=512

Set permissions for the swap file (globally readable swap files are a major local vulnerability):

# chmod 600 /swapfile

After creating the swap file, format it:

# mkswap /swapfile

mkswap output

Tip: A UUID will be displayed here, but it’s useless.

Enable the swap file:

# swapon /swapfile

Finally, edit /etc/fstab and add the following line:

/etc/fstab
/swapfile none swap defaults 0 0

Configuring Hibernation (Reference: Arch Wiki)

Configuring GRUB

GRUB configuration

Setting resume (to tell the system which disk device to resume from)

Get the UUID of the partition containing the swap file. For example, I’m using LVM:

lsblk -no UUID /dev/XzRoot/root

View UUID

Fill in this UUID (2cee6498-2bd1-496f-9801-164ddddcc9c3) for resume:

resume=UUID=2cee6498-2bd1-496f-9801-164ddddcc9c3

Alternatively, you can use resume=/dev/XzRoot/root.

Getting resume_offset

Run sudo filefrag -v /swapfile

filefrag output

Find the first number with two dots in the first row. As shown in the screenshot, it’s: 78610432.

Setting resume_offset (to tell the system the exact location to resume from)

Fill in the value obtained from the swap file (resume_offset) as shown:

resume_offset=78610432

Regenerate grub.cfg

grub-mkconfig -o /boot/grub/grub.cfg

Configuring Kernel Module

Edit the HOOKS entry in mkinitcpio.conf

For runtime hook keywords, refer to ArchWiki.

Add the resume hook:

# /etc/mkinitcpio.conf
HOOKS=(base udev autodetect modconf block lvm2 resume filesystems keyboard fsck)

Recompile the image

sudo mkinitcpio -p your_kernel_name

The End

Before hibernating for the first time, a reboot is required to activate the feature.

After rebooting, you should see the hibernation option in the power menu.