Suspend and hibernate

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This article describes how to suspend or hibernate a Gentoo system.



Make sure support for suspend and hibernation has been activated (CONFIG_SUSPEND) and (CONFIG_HIBERNATION):

Power management and ACPI options --->
    [*] Suspend to RAM and standby
    [*] Hibernation (aka 'suspend to disk')


One of the following packages can be used to control the in-kernel default suspend/hibernate implementation, namely, swsusp.

Available suspend modes

To see available suspend modes use

root #cat /sys/power/state

for swsusp, default implementation.

Those two file will list at least ACPI S2/4 power down methods on modern hardware. New hardware would also support S5 method which is a rough S4 method. ACPI S2 correspond to suspend to ram (ram method in swsusp terms and 3 in ToI terms); S4 hibernation to disk (disk in swsusp terms and 4 in ToI terms; S5 hibernation to disk (5 in ToI terms).

Swsusp users can choose between platfom, meaning ACPI, or shutdown methods which can be echo-ed to /sys/power/disk sysfs file.

Suspend to RAM

Preferred commands to suspend are:

root #s2ram

or, if using elogind

root #loginctl suspend

For suspend (to ram) for hibernate-script users:

root #hibernate-ram


root #hibernate

to hibernate (to disk.)

A more raw method is to

root #echo mem > /sys/power/state

Suspend to disk


If you are using genkernel initramfs, you may experience bug #156445 which makes it impossible to resume after suspend-to-disk. There is a number of ways to avoid it, from editing initramfs (e.g. as described here) to dropping genkernel completely.

For suspend to disk to operate a swap partition or swap file must exist.

The swap file should be active beforehand and should be echoed on the appropriate file before any attempt to suspend/hibernate.

root #echo /dev/sda1 > /sys/power/resume

A more raw method is to:

root #echo disk > /sys/power/state

Do not forget to probe:

root #cat /sys/power/tuxonice/swap/headerlocations

before issuing an actual command and append the result to kernel command line argument prepended with `resume='. This will suffice to resume from a block device or swap file for ToI. However, it's more complicated for a swapfile with swsusp.

Suspend to disk with sys-auth/elogind

First, make sure a swap partition has been set, grub.cfg rebuilt and the initramfs (if any) updated as shown above.

Reboot the system:

root #loginctl reboot

Next, try

root #loginctl hibernate

Suspend to disk with swapfile

You can use suspend to disk with a swapfile. When you have a functional swapfile you need to configure kernel parameters (via GRUB, etc.).

First find UUID of device where your swapfile resides. For example: /dev/sda1.

If swapfile resides in a LVM volume, GRUB must be compiled with LVM support. Otherwise, the system will not wake up and will be cold started.
root #blkid /dev/sda1

Find offset of swapfile on given partition using swap-offset utility from sys-power/suspend:

root #swap-offset /path/to/swapfile

After that edit GRUB config and add required parameters to boot string:

FILE /etc/defaults/grubGRUB defaults
GRUB_CMDLINE_LINUX_DEFAULT="resume=UUID=<UUID_of_partition> resume_offset=<offset_of_swapfile>"

Rebuild GRUB config:

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

Reboot the system and check used kernel parameters:

user $cat /proc/cmdline

It should now be possible to hibernate the system.

Btrfs requires you to compute the offset of the swap file a different way, see Arch Linux wiki, Hibernation into a swap file on Btrfs.

Remember, swap file must contain all memory used by running processes and memory based filesystems like tmpfs or zram prior to hibernating. However, unless specifically set, the hibernation image is compressed. Setting hibernation image size to half of the amount of installed RAM is a safe value in most cases. One of the cases where this does not fully apply is when the system has a high usage of zswap which means that memory may already be compressed.


Classic kernel buffer comes handy:

user $dmesg

Can not resume after suspend

In case resuming from suspend does not work, disable the security chip setting in BIOS/UEFI and try again. If using the i915 driver, try disabling CONFIG_RETPOLINE but keep in mind that it implies the vulnerability of Spectre v2.

Wifi stays hard blocked

Although possibly unsafe, tricking the bios into believing it being "Windows" might solve it.

This can be done by adding acpi_osi=! acpi_osi=Windows or acpi_osi=! acpi_osi='Windows 2009'(kernel source) to the boot command line options.

For sys-boot/grub, it can be appended to GRUB_CMDLINE_LINUX in /etc/default/grub.

Migration from pm-utils to elogind

Copy any suspend/resume and hibernate/thaw hook scripts from the directory /etc/pm/sleep.d/ to /lib64/elogind/system-sleep/, and modify them to cater for the new $1 ('pre' or 'post') and $2 ('suspend', 'hibernate', or 'hybrid-sleep'). See also: elogind#Hook_scripts_to_be_run_when_suspending.2Fhibernating_and.2For_when_resuming.2Fthawing

See also

External resources