Power Management

System 2026-08-28

Shanios ships sane power defaults that are active from first boot — no post-install tuning required. This page focuses on laptops: sleep states, suspend, hibernation, battery reporting, and the tunables worth knowing about. Desktop users can ignore most of it.

What works out of the box:

Lid-close suspend, handled by systemd-logind
Battery reporting via upower, surfaced by every desktop's power panel
Airplane-mode radio toggles via rfkill
Correct clock across suspend/hibernate via timedatectl / systemd-timesyncd (enabled by default)

Sleep States

Modern Linux systems support two suspend-to-RAM variants:

State	Name	Behavior
`s2idle`	Suspend-to-idle (aka "modern standby")	CPU halted, devices put in low-power mode, RAM kept refreshed. Fastest wake, higher drain.
`deep`	S3	Traditional ACPI sleep — RAM self-refreshes, everything else powered off. Slowest wake, minimal drain.

Which states your hardware supports is firmware-dependent. Check what's available and what's currently selected:

cat /sys/power/mem_sleep
# Example output: s2idle [deep]
#                 ^^^^^^ the bracketed entry is the active default

If only s2idle appears, your firmware does not expose S3 — nothing to configure. Many recent laptops ship s2idle-only.

Suspend

# Suspend immediately
systemctl suspend

# Inspect your current session (shows idle/lid-relevant state)
loginctl session-status

By default, closing the lid suspends the machine — on battery and on AC (HandleLidSwitch=suspend is the logind default). Wake with the power button; most firmware also wakes on keyboard input if enabled in BIOS/UEFI setup.

Hibernation

Hibernation writes RAM to swap and powers off completely — survives a dead battery, unlike suspend.

Requirements:

Swap at least as large as RAM. Shanios creates a swapfile sized to RAM in the dedicated @swap Btrfs subvolume (mounted at /swap) at install time.
resume= on the kernel command line. This is already baked into the image's UKI cmdline at build/deploy time — there is nothing to configure manually.

Do not attempt to add or edit boot arguments yourself: the bootloader editor is disabled by design on Shanios, and any resume setup belongs in the image. If you resized or replaced the swapfile manually, see Storage for the correct procedure first.

# Hibernate
systemctl hibernate

Verify a full hibernate/resume cycle works before relying on it — a failed resume falls back to a cold boot with an empty session.

Battery & Reporting

# Full battery report: capacity, health, vendor, cycle count where exposed
upower -i $(upower -e | grep BAT)

# Just charge state and percentage
upower -i $(upower -e | grep BAT) | grep -E 'state|percentage|capacity'

The capacity field is firmware-reported health (design vs. full-charge capacity) — below ~80% usually means a worn battery. Every desktop surfaces this graphically:

GNOME: Settings → Power
KDE Plasma: System Settings → Energy Saving
COSMIC: Settings → Power

Tunables

Lid Actions

Lid behavior is configured in /etc/systemd/logind.conf. The writable /etc overlay persists across updates, so edits survive redeploys.

# /etc/systemd/logind.conf
HandleLidSwitch=suspend                    # lid close on battery
HandleLidSwitchExternalMemory=ignore       # lid closed while docked/external monitor
HandleLidSwitchDocked=ignore               # docked via dock itself

After editing:

sudo systemctl restart systemd-logind

Restarting systemd-logind briefly resets login sessions — running graphical sessions generally survive, but expect a short hiccup and re-authentication prompts.

Wi-Fi Power Save

NetworkManager manages Wi-Fi power saving per connection via the wifi.powersave property. See Wi-Fi & Wireless Firmware for checking and changing it.

USB Autosuspend

USB autosuspend saves power but can misbehave with some input devices (mice/keyboards stuttering or dropping after idle). If a wired input device acts up after a pause, that's autosuspend — check /sys/bus/usb/devices/*/power/control and consider whitelisting the device rather than disabling autosuspend globally.

Troubleshooting

Issue	Solution
Wakes immediately after suspend	Commonly a firmware ACPI issue with the active sleep state. Toggle between `deep` and `s2idle`: `echo deep > /sys/power/mem_sleep` (as root), then retry. Persist the choice with a tmpfiles entry (below)
Suspends fine, black screen on wake	Usually a GPU driver pairing problem. Confirm you booted the slot matching your latest deployment: `cat /data/current-slot`; reboot once to settle. If it persists across slots, report the bug with GPU model
Hibernation writes swap but doesn't resume	Swap smaller than RAM, or the wrong swap target — see Storage for swap sizing and the baked-in `resume=` handling
Battery drains overnight while suspended	Check which state you're using: `s2idle` drains far faster than `deep` — prefer `deep` when supported. Also rule out Wake-on-LAN keeping the NIC alive (`ethtool` — see Network Tools)
Lid ignored on AC	`HandleLidSwitchExternalMemory=ignore` is the logind default for external-monitor setups. Change it in `/etc/systemd/logind.conf` if you want suspend-on-AC

Persisting a mem_sleep choice across reboots (tmpfiles write it early each boot):

# /etc/tmpfiles.d/mem-sleep.conf
w /sys/power/mem_sleep - - - - deep

Filtering the journal for sleep activity:

journalctl --grep 'suspend|sleep|resume' -b
journalctl -u systemd-suspend.service -b -1   # previous suspend attempt