Laptop Suspend & Hibernate

Basic Concepts

Mode	Name	Description
Suspend	Suspend (S3)	State saved to RAM, low power, fast resume
Hibernate	Hibernate (S4)	State written to disk swap, fully powered off, slower resume
Hybrid Sleep	Hybrid Sleep	State saved to both RAM and disk, balancing speed and safety

Testing Suspend


# Suspend to RAM
sudo systemctl suspend
 
# Check supported sleep modes
cat /sys/power/state

Configuring Hibernate

Prerequisites

Hibernate requires swap space no smaller than the physical memory size.


# Check memory and swap
free -h
 
# Check swap partition/file
swapon --show

Using a Swap File for Hibernate

If using a swap file instead of a swap partition:


# Create a swap file equal to RAM size (example: 16GB)
sudo fallocate -l 16G /swapfile
sudo chmod 600 /swapfile
sudo mkswap /swapfile
sudo swapon /swapfile
 
# Write to /etc/fstab for persistence
echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab

Configuring Kernel Parameters

Find the physical offset of the swap file:


sudo filefrag -v /swapfile | head -4

Note the physical_offset value from the first row. Then find the UUID of the partition containing the swap file:


findmnt -no UUID -T /swapfile

Edit the GRUB configuration:


sudo nano /etc/default/grub

Modify GRUB_CMDLINE_LINUX_DEFAULT:


GRUB_CMDLINE_LINUX_DEFAULT="quiet splash resume=UUID=YOUR_UUID resume_offset=OFFSET_VALUE"

Update GRUB and initramfs:


sudo update-grub
# Ubuntu 26.04 generates the initramfs with Dracut by default:
sudo dracut -f --regenerate-all
# On legacy initramfs-tools systems use instead: sudo update-initramfs -u -k all

Testing Hibernate


sudo systemctl hibernate

Hybrid Sleep


sudo systemctl hybrid-sleep

Lid Close and Power Button Behavior

Edit /etc/systemd/logind.conf:


[Login]
HandleLidSwitch=suspend
HandleLidSwitchExternalPower=ignore
HandlePowerKey=poweroff
HandleSuspendKey=suspend

Available values: ignore, poweroff, reboot, halt, suspend, hibernate, hybrid-sleep, lock

Restart the service after making changes:


sudo systemctl restart systemd-logind

Common Issues

Cannot wake up after suspend

Check kernel logs:


journalctl -b -1 | grep -i "suspend\|resume\|sleep"

Try adding kernel parameters in GRUB:


acpi_osi=Linux acpi_backlight=vendor

For NVIDIA GPU users, make sure the driver version is recent and power management is enabled:


sudo systemctl enable nvidia-suspend nvidia-resume nvidia-hibernate

Cannot resume after hibernate

Confirm that the resume parameters are correctly configured, and check whether initramfs includes the resume module:


# Ubuntu 26.04 uses Dracut by default; list initramfs contents with lsinitrd:
sudo lsinitrd /boot/initrd.img-$(uname -r) | grep resume
# On legacy initramfs-tools systems use instead: lsinitramfs /boot/initrd.img-$(uname -r) | grep resume

Wi-Fi unavailable after wake


sudo systemctl restart NetworkManager
# Or reload the wireless module
sudo modprobe -r iwlwifi && sudo modprobe iwlwifi

Bluetooth unavailable after wake


sudo systemctl restart bluetooth
sudo rfkill unblock bluetooth

Power Management Optimization

Install TLP for laptop power optimization:


sudo apt install tlp tlp-rdw
sudo systemctl enable tlp
sudo tlp start

Check battery status:


tlp-stat -b