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uswsusp (userspace software suspend) is a set of user space tools used for hibernation (suspend-to-disk) and suspend (suspend-to-RAM or standby) on Linux systems. It consists of:
- s2ram - a wrapper around the kernel's suspend-to-RAM mechanism allowing the user to perform some graphics adapter manipulations from the user land before suspending and after resuming that may help to bring the graphics (and the entire system) back to life after the resume. Incorporates the functionality of vbetool and radeontool as well as some tricks of its own. Includes a list of working hardware configurations along with the appropriate sets of operations to be performed to resume them successfully. This is accomplished by a hardware whitelist maintained by HAL - s2ram translates the HAL database options into s2ram parameters.
- s2disk - the reference implementation of the userspace software suspend (µswsusp); it coordinates the steps necessary to suspend the system (such as freezing the processes, preparing the swap space, etc.) and handles image writing and reading. s2disk already supports compression and encryption of the image and other features (e.g. a nice progress bar, saving the image on a remote disk, playing tetris while resuming, etc.) can be easily added.
- s2both - combines the funtionalities of s2ram and s2disk and it's very useful when the battery is almost depleted. s2both writes the system snapshot to the swap (just like s2disk) but then puts the machine into STR (just like s2ram). If the battery has enough power left you can quickly resume from STR, otherwise you can still resume from disk without losing your work.
You must edit
/etc/suspend.conf before attempting to suspend to disk.
- If using a swap partition:
resume device = /dev/disk/by-label/swap
/dev/disk/by-label/swap must be replaced with the correct block device containing the swap partition.
- If using a swap file:
resume device = /dev/sdX # the partition which contains swapfile resume offset = 123456
where 123456 is the offset from the beginning of the resume device where the swap file's header is located. To obtain the offset, you can check Swap file resuming. The resume offset can be obtained by running
# swap-offset your-swap-file
image sizeparameter (optional) can be used to limit the size of the system snapshot image created by s2disk. If it's not possible to create an image of the desired size, s2disk will suspend anyway, using a bigger image. If image size is set to 0, the image will be as small as possible.
shutdown methodparameter (optional) specifies the operation that will be carried out when the machine is ready to be powered off. If set to "reboot" the machine will be rebooted immediately. If set to "platform" the machine will be shut down using special power management operations available from the kernel that may be necessary for the hardware to be properly reinitialized after the resume, and may cause the system to resume faster.
- If the
compute checksumparameter is set to 'y', the s2disk and resume tools will use the MD5 algorithm to verify the image integrity.
- If the
compressparameter is set to 'y', the s2disk and resume tools will use the LZF compression algorithm to compress/decompress the image.
splashis set to 'y', s2disk and/or resume will use a splash system. Currently splashy and fbsplash are supported.
resume pauseoption will introduce a delay after successfully resuming from hibernation, in order to allow the user to read the stats (read and write speed, image size, etc.)
threadsis enabled, s2disk will use several threads for compressing, encrypting and writing the image. This is supposed to speed things up. For details, read the comments in suspend.c
Support for encryption
- generate a key with the suspend-keygen utility included in the package;
- write the name of the key in
encrypt = y RSA key file = <path_to_keyfile>
/etc/mkinitcpio.conf file and add "uresume" to the HOOKS entry.
HOOKS="base udev autodetect pata scsi sata uresume filesystems"
- rebuild the ramdisk
# mkinitcpio -p linux
snapshot device = /dev/snapshot resume device = /dev/disk/by-label/swap # image size is in bytes image size = 1468006400 #suspend loglevel = 2 compute checksum = y compress = y #encrypt = y #early writeout = y #splash = y # up to 60 (seconds) #resume pause = 30 threads = y
To suspend to disk, run:
To suspend to ram, first run:
# s2ram --test
to see if your machine is in the database of machines known to work. If it returns something like "Machine matched entry xyz" then go ahead and run:
Otherwise, the --force parameter will be necessary, possibly combined with other parameters (see
s2ram --help). It may fail.
Now you could try to suspend directly calling s2disk from the command line:
It is probably necessary to resort to a userspace tool which calls internally s2disk, like Pm-utils or hibernate-script. See Suspending to Disk with hibernate-script about details for defining the ususpend-disk method as default.
This way, pm-suspend and pm-hibernate will use uswsusp. There is an advantage to this: regular users can use these commands to suspend with uswsusp:
$ dbus-send --system --print-reply --dest="org.freedesktop.UPower" /org/freedesktop/UPower org.freedesktop.UPower.Suspend $ dbus-send --system --print-reply --dest="org.freedesktop.UPower" /org/freedesktop/UPower org.freedesktop.UPower.Hibernate
To to put your system into hibernation a.k.a Suspend to Disk with
systemctl hibernate, do:
# cp /usr/lib/systemd/system/systemd-hibernate.service /etc/systemd/system/ # cd /etc/systemd/system/
systemd-hibernate.service with your preferred text editor and edit the line from this:
... ExecStart=/usr/lib/systemd/systemd-sleep hibernate
... ExecStart=/bin/sh -c 's2disk && run-parts --regex .\* -a post /usr/lib/systemd/system-sleep'
After that, execute
systemctl hibernate to put your system into hibernation. Do similar changes for systemd-hybrid-sleep.service to enable uswsusp-based hybrid sleep too.