CachyOS Gamescope Boot Wizard

Turn a CachyOS desktop PC into a SteamOS-style console: it boots straight into Steam's Big Picture (gamescope), and you can switch to the KDE Plasma desktop and back whenever you like - just like on a Steam Deck or Valve's Steam Machine.

Out of the box, CachyOS doesn't quite manage this: the switch to the desktop can hang, and the PC doesn't reliably boot back into gaming mode. This script fixes that and sets everything up for you.

What you get

The wizard is a menu: pick what you want, and it turns each part on or off. Everything you turn off is put back the way it was.

1. SteamOS conversion - boots straight into gaming mode, Switch to Desktop in Steam works and so does going back (the Return to Gaming Mode icon on the desktop), you're back in gaming mode after a restart, and Steam's on-screen keyboard (Steam + X) also works on the desktop.
2. SteamOS theme - the Vapor look for the desktop (CachyOS's cachyos-vapor package).
3. Steam Deck/Machine icons - Steam Deck button icons in gaming mode.
4. Single user mode - like SteamOS: never a login or lock screen, no user switching or logging out. Typing a password with a controller is no fun. (Needs 1.)
5. Steam Machine support - only shown on a Valve Steam Machine: the driver for the front LED bar, and the hardware settings in Steam (fan, TV control over HDMI-CEC).

Requirements

• CachyOS with the KDE Plasma desktop (the default CachyOS Desktop edition)
• Your normal user account, with permission to use sudo

Installation

Open Konsole on your Plasma desktop and run:

curl -fsSL https://github.com/theupriser/cachyos-gamescope-boot/releases/latest/download/setup-gamescope-boot.sh | bash

That downloads and runs the latest single-file version, and works in any shell, including fish (CachyOS's default). Prefer to keep a copy, or to look at the script first? Clone the repository instead:

git clone https://github.com/theupriser/cachyos-gamescope-boot.git
cd cachyos-gamescope-boot
./setup-gamescope-boot.sh

Run it as yourself, not as root. You'll see a checklist:

   [x] SteamOS conversion: boot into gaming mode, Steam on the desktop  (now: off)
 > [x] Install SteamOS theme: Vapor look (cachyos-vapor)  (now: off)
   [x] Install Steam Deck/Machine icons: Deck button icons in gaming mode  (now: off)
   [x] Single user mode: no password, lock screen or log out (SDDM)  (now: off)

  Kernels (> = running; controller = Steam controller driver, LEDs = LED bar driver built)
    6.18.52-1-cachyos-lts   linux-cachyos-lts  headers yes  controller yes
  > 7.2.7-1-cachyos         linux-cachyos      headers yes  controller yes

  Up/Down move   Space select   Enter run   a run + re-apply what's on   q quit

Move with the arrow keys, tick or untick with Space, and press Enter to run. "now:" shows what's on at the moment. Below the list, every installed kernel is shown with its headers and Steam controller driver; on a Steam Machine also whether the LED bar driver is built for it, and whether it's loaded right now, so a kernel update is easy to check. The wizard then shows what it will change, asks your password once, and at the end offers to restart (needed for changes to how the PC starts).

Run it again whenever you like - to change your choices, to turn things off again, or after a CachyOS update (press a in the menu to re-apply everything that's on).

If you cloned the repository, keep the whole folder: the script needs the files in lib/ next to it.

Using it

• To the desktop: in gaming mode, open the Steam menu and choose Power > Switch to Desktop.
• Back to gaming mode: double-click Return to Gaming Mode on the desktop (or log out, if you're not using single user mode).
• After a restart you always start in gaming mode.

Prefer to decide yourself where your PC starts? Run one of these in Konsole:

steamos-session-select persistent  # start where you left off last time
steamos-session-select oneshot     # always start in gaming mode (default)

If something goes wrong

Gaming mode shows a black screen or keeps restarting. Press Ctrl+Alt+F3, log in with your username and password, and run:

sudo /usr/lib/steamos/steam-set-session plasma.desktop && sudo systemctl restart display-manager

That takes you back to the desktop.

The LED bar on the Steam Machine stays dark. Restart the PC once more; a freshly installed driver often needs a reboot. Still dark? See Front LED bar under technical details.

Undo something: run the wizard again and untick it.

---

Technical details

How turning things on and off works

At startup every component checks whether it is on (*_status in lib/). You choose; the wizard then turns off what you unticked (in reverse order) and turns on what you ticked. To be able to undo:

• System files are backed up once, next to the original, with a .bak-gamescope-wizard suffix, and restored when you turn the component off.
• KDE settings in your home directory are recorded with their previous value the first time the wizard changes them, in an undo journal under ~/.local/state/cachyos-gamescope-boot/. Turning the component off writes the old values back (or removes keys that didn't exist before). Setups made by older versions of the script, without a journal, fall back to KDE's defaults.
• Packages installed for the conversion (Steam, gamescope-session, ...) are kept when you turn it off; Steam Machine support removes its own.

Single user mode: SDDM, no locking

Turning it on switches to SDDM and turns off everything that asks for a password or another user, per user: action/lock_screen, switch_user and start_new_session restrictions in kdeglobals, no automatic locking (kscreenlockerrc), Meta+L and Ctrl+Alt+Del unbound, and the launcher shows only Sleep / Restart / Shut Down (kickoff primaryActions=3), which hides the Session dropdown with Log Out. (Restricting action/logout would also hide Restart and Shut Down.) Turning it off restores all of that and moves the conversion back to plasma-login-manager.

SDDM is what SteamOS uses, and CachyOS's steam-set-session supports it directly: it writes /etc/sddm.conf.d/zz-steamos-autologin.conf, which SDDM honours. The script installs and enables sddm (active from the next boot), writes User=, Session= and Relogin=true to /etc/sddm.conf.d/10-gamescope-autologin.conf, and removes any [Autologin] from /etc/sddm.conf (read last, so it would override both). No sync bridge or sudoers rule is needed; the shortcut just runs steamos-session-select gamescope, which logs out, and Relogin=true logs straight back in to gamescope.

Without single user mode, the conversion uses plasma-login-manager (CachyOS's default since March 2026), which needs the workarounds below.

Why this is needed (plasma-login-manager)

CachyOS's gamescope-session-cachyos package ships steamos-session-select, which is meant to work exactly like it does on real SteamOS. Since the March 2026 release, CachyOS uses plasma-login-manager instead of SDDM, and three things get in the way:

1. No User= written to the autologin config. steam-set-session (called by steamos-session-select) only writes a Session= key. plasma-login-manager needs both Session= and User= to autologin at all; without User= it shows the greeter every boot.

2. Missing /etc/plasmalogin.conf.d directory. Without it, steam-set-session fails, and Steam's "Switch to Desktop" hangs forever. (Fixed upstream in gamescope-session-cachyos 1.1.6; the script still creates the directory for older versions.)

3. The base /etc/plasmalogin.conf wins over conf.d, and CachyOS ships it with Session=plasma. Every tool that changes sessions (steamos-session-select, Steam's power menu, and cachyos-gamescope-autologin.service, which resets you to gamescope after a desktop session) only writes /etc/plasmalogin.conf.d/zz-steamos-autologin.conf. The base file takes priority, so none of those switches stick.

The script sets Session=, User= and Relogin=true in the base config, and installs a small systemd path watcher that copies whatever CachyOS's tools write to the conf.d fragment into the base config.

What each component changes

SteamOS conversion (lib/login-manager.sh, lib/steam-desktop.sh, lib/desktop-shortcut.sh):

• installs missing packages: gamescope-session-cachyos, steam, mangohud, xterm, ttf-liberation, wqy-zenhei, plasma-keyboard;
• SDDM (single user mode): installs/enables SDDM and writes its autologin config;
• plasma-login-manager: creates /etc/plasmalogin.conf.d, backs up and rewrites the [Autologin] section of /etc/plasmalogin.conf, removes stray zzz-steamos-autologin*.conf files from manual troubleshooting (never zz-steamos-autologin.conf, which CachyOS's tools own), and installs /usr/local/bin/sync-steamos-session.sh plus sync-steamos-session.path/.service;
• KWIN_IM_SHOW_ALWAYS=1 for the virtual keyboard and a steam-desktop-autostart systemd user service that starts Steam silently in Plasma only;
• the Return to Gaming Mode shortcut; on plasma-login-manager with a narrow sudoers rule (/etc/sudoers.d/gamescope-session-switch) so it can restart the login manager without a password prompt.

Turning it off restores /etc/plasmalogin.conf from its backup, removes the SDDM autologin, sync bridge, shortcut, sudoers rule and Steam autostart, and switches back to plasma-login-manager.

Steam Deck/Machine icons: STEAM_GAMEPADUI_ARGS="-gamepadui -steamos3" in ~/.config/environment.d/ (and gamescope-session's own environment file), which makes Steam show Steam Deck button glyphs in gaming mode.

SteamOS desktop look

Installs CachyOS's cachyos-vapor package (the SteamOS Vapor theme the CachyOS handheld edition uses) from the CachyOS repository and switches your desktop to its Vapor global theme, including its desktop and window layout (like ticking "Desktop and window layout" in System Settings): Vapor colors and Plasma style, the SteamOS panel and launcher icon, and the Steam Deck wallpaper. Run it from the Plasma desktop: applying the layout needs a running Plasma session.

It also adds the SteamOS desktop extras that cachyos-vapor doesn't ship, taken from the newest steamdeck-kde-presets on Valve's SteamOS mirror (checksum verified) and installed to /usr/local:

• Add to Steam in the right-click menu of apps, AppImages and .exe files, and in the launcher: adds them to Steam as non-Steam games;
• Nested Desktop: add it to Steam from the launcher, then start it in gaming mode for a Plasma desktop inside gaming mode;
• the SteamOS Return to Gaming Mode icon (Steam logo with a return arrow);
• a window rule that keeps the Steam keyboard above other windows;
• an empty, password-less KWallet, only if you don't have a wallet yet, so nothing asks for a wallet password after autologin.

Turning it off restores your previous look and panel layout, and removes cachyos-vapor again if the wizard installed it (and nothing else, like cachyos-handheld, needs it).

Front LED bar (Steam Machine)

The Steam Machine support component, only shown on Fremont hardware (DMI Valve/Fremont, or OEM/F7F on early units):

• installs an AUR helper (yay) if neither yay nor paru is present;
• installs the kernel headers for every installed kernel;
• installs leds-valve-dkms-git from the AUR - Valve's own driver from the SteamOS kernel - builds it for every installed kernel (so the LTS kernel works too), and loads it at every boot (/etc/modules-load.d/leds-valve.conf);
• adds a udev rule (/etc/udev/rules.d/70-valve-leds-user.rules) that gives your user the LED files, so Steam, which runs as you, can drive the bar;
• console-like power button: it puts the machine to sleep, and it never suspends by itself on mains power (the launcher's Shut Down still shuts down);
• installs and enables steamos-manager, the service Steam in gaming mode uses for hardware settings (fan, HDMI-CEC, performance); it recognises the Steam Machine from its DMI data.

Turning it off removes all of that again (the AUR helper is kept).

The LEDs appear as /sys/class/leds/valve-leds*. The driver's Makefile builds against the running kernel (uname -r) instead of the kernel DKMS builds for, so the wizard adds a DKMS override (/etc/dkms/leds-valve-dkms.conf) that passes DKMS's target kernel in. With it, DKMS rebuilds the driver whenever a kernel or its headers are installed or upgraded. A newly added kernel doesn't come with its headers, so ensure-kernel-headers.service checks at every boot and installs any missing -headers package, which makes DKMS build the driver for it.

Troubleshooting:

dkms status
ls -l /sys/class/leds/valve-leds*/
sudo dmesg | grep -i valve
cat /var/lib/dkms/leds-valve-dkms/0.1/build/make.log
journalctl --user -b | grep -i led

BIOS updates are not part of the wizard. Valve ships the Steam Machine BIOS as F7F0108.cab in its fremont-hw-support package for fwupd. To install it by hand (keep the machine on mains power and don't interrupt it):

sudo dmidecode -s bios-version     # current version
sudo pacman -S fwupd
curl -LO https://steamdeck-packages.steamos.cloud/archlinux-mirror/holo-3.9/os/x86_64/fremont-hw-support-20260807.1-1-any.pkg.tar.zst
mkdir fhw && tar -I zstd -xf fremont-hw-support-*.pkg.tar.zst -C fhw
sudo fwupdmgr install fhw/usr/share/fwupd/remotes.d/fremont/firmware/F7F0108.cab

Manual session control

steamos-session-select gamescope   # switch to gamescope right now
steamos-session-select plasma      # switch to desktop right now
steamos-session-select persistent  # remember the last-used session across reboots
steamos-session-select oneshot     # always start in gamescope (default, like a Deck)

With Relogin=true, a gamescope session that fails to start is restarted immediately, which can turn into a loop - hence the Ctrl+Alt+F3 escape above.

Removing everything

Run the wizard and untick everything. Afterwards the PC boots to the normal CachyOS login screen again; packages installed for the conversion (Steam, gamescope-session, ...) stay installed.

Project layout

File	Responsibility
setup-gamescope-boot.sh	Entry point: checks, menu, apply, summary, restart
lib/menu.sh	The menu: detect, toggle, plan and apply changes
lib/state.sh	Undo journal for KDE settings (kset/krevert)
lib/common.sh	Output helpers, prompts, backups, plasmashell handling
lib/packages.sh	Required packages, AUR helper (yay/paru)
lib/login-manager.sh	SteamOS conversion: SDDM or plasmalogin autologin, sync bridge
lib/steam-desktop.sh	Steam in the Plasma session; Steam Deck/Machine icons
lib/desktop-shortcut.sh	Return to Gaming Mode shortcut and its sudoers rule
lib/vapor-theme.sh	SteamOS theme: installs and switches to cachyos-vapor
lib/steamos-extras.sh	SteamOS desktop extras from Valve's package (Add to Steam, Nested Desktop, icon, keyboard rule, KWallet)
lib/single-user.sh	Single user mode: no lock screen, user switching or log out
lib/steam-machine.sh	Steam Machine support: LED driver, LED access, steamos-manager
.github/tools/bundle.sh	Builds the single-file version (dist/setup-gamescope-boot.sh)
.github/workflows/bundle.yml	Builds and checks it on every push; publishes it on main

The single-file version is generated: on every push to main, GitHub Actions runs .github/tools/bundle.sh, checks the result with bash -n and shellcheck, and publishes it as a release per version (tag v<VERSION>, never overwritten; the newest is marked latest, and the latest tag follows it). It inlines lib/*.sh and wraps the entry point in main(), so bash has read the whole file before anything runs; when stdin is a pipe (curl | bash) it reattaches the terminal for the menu (set WIZARD_KEEP_STDIN=1 to keep piped input).

Notes for contributors and AI coding agents are in AGENTS.md.

Caveats

• This works around CachyOS/plasma-login-manager behavior as of September 2026. If CachyOS fixes steam-set-session upstream, parts of this script become unnecessary - please open an issue or PR if you notice that.
• Tested on a Valve Steam Machine running CachyOS Desktop edition. It should work on any CachyOS desktop install using plasma-login-manager, but hasn't been tested on Steam Deck/Legion Go hardware.

Related upstream reports

• CachyOS/gamescope-session#9 - "Switch to Desktop" hang due to missing /etc/plasmalogin.conf.d

License

MIT - do whatever you want with it.