yserver

A modern X11 server written from scratch in Rust.

The goal is not to clone Xorg. It is to provide a practical X11 server that runs real desktop environments, window managers, and applications on modern Linux while dropping legacy baggage (non-TrueColor visuals, indirect GLX, the DDX driver ABI, endian-swapped clients, and so on).

See docs/high-level-design.md for the full design and scope.

Name

The yserver name is the 'working' name as it was the first idea that popped into my head when starting the project. But there are multiple projects on GitHub with this name (but none for X11 servers), the name is subject to change. Not a priority now.

Status

yserver (standalone DRM/KMS) can run full desktop environments.

You can run your steam games on yserver and have it perform 'almost' on par with Xorg. Please try it out and report.

See docs/extensions.txt for a list of all supported/implemented extensions.

Recent work

• Windows (x86_64 and aarch64): X clients from WSL or other machines show up on the Windows desktop, each in its own window or in one rooted window, with a shared clipboard, a Settings dialog and DPI awareness
• macOS: yserver runs in a window on Apple Silicon (Mesa KosmicKrisp), with a Dock icon and a Settings window; rootless mode gives every X window its own Mac window
• OpenBSD support
• variable refresh rate on the monitor a fullscreen client is scanned out to (--vrr) (@ariel3259)
• --vrr all: VRR for NVIDIA clients too, honouring the NVIDIA and Mesa application lists (@ariel3259)
• tearing on demand: fullscreen clients that ask for async flips get uncapped direct scanout (@ariel3259)
• hardware cursor on atomic KMS: a cursor plane per CRTC, and cursor changes no longer drop direct scanout (@ariel3259)
• gamma through atomic GAMMA_LUT (@ariel3259)
• multi-monitor: direct scanout across monitors whose refresh rates differ slightly; switching off or unplugging one monitor no longer blanks the others; xrandr changes to one output leave the others alone
• compositors: redirected windows keep their own and their subwindows' borders (@SetZero), and draw at the right offset when resized; no more blank windows after a workspace switch under picom; no more smudged decorations when resizing under fvwm + xcompmgr
• less CPU in the core loop: a client's socket is only polled for writing while output is waiting (@SetZero)
• XKB modifier locks apply and survive setxkbmap (@petrovo-as)
• RENDER text no longer loses glyphs after a long session
• no more crash when a window tree is destroyed while windows in it are still in use (#297); window teardown follows Xorg's order for grabs, focus, selections and Present
• clipboard and selection events go to the client that set the owner, as on Xorg, and a second window manager is refused instead of fighting the first

Previously

• CDE (the Common Desktop Environment) runs: dtsession, dtwm with its panel, dtterm, dtfile, dtpad, and the Motif/Xaw apps around it

• old-style toolkits (Motif, Xaw, Tk, xterm) draw like on Xorg: lines, text and clipping, exposures and GraphicsExpose, GetImage of windows with children

• CDE and Motif apps start as fast as on Xorg

• font lookups are indexed and cached

• compressed bitmap fonts now work as expected

• fractional scaling via RANDR transforms (Cinnamon 125%/150%, xrandr --scale), screen rotation and reflection, virtual monitors (xrandr --setmonitor), and

• xrandr --dpi now works

• RECORD extension (pynput and other global input listeners)

• one XInput device per physical device (mouse, keyboard and touchpad, as on Xorg) (@ariel3259)

• runs on Vulkan 1.2 GPUs such as Intel Haswell and Ivy Bridge; older drivers get a clear error naming what is missing

• XFCE dialogs under the compositor keep their button bar when scrolled; MATE tray icons keep their pixels when moved

• the Cinnamon lock screen shows up again, and fullscreen windows can be re-composited after leaving fullscreen

• fix slow VRAM growth: the cache of freed pixmaps is capped, and pixmaps held by GCs and freed cursors are released

• window backgrounds no longer flash in odd colours (CDE with sloppy focus)

• lower CPU use with x11vnc and other screen grabbers

• xmodmap and xkbcomp changes reach XKB clients; XI2 raw key events

• a regression suite that runs the real server in a VM and compares it with Xorg, in CI

• XDMCP session negotiation with a display manager, and a TCP listener — both optional Cargo build features, off by default; see docs/setup.md

• X11 server-side window borders, solid and tiled (awesome)

• damage-clipped repaint on non-composited desktops: only what changed is redrawn, cutting compositing GPU load to roughly a third

• direct compositor scanout — a fullscreen compositor pixmap is flipped straight to the CRTC instead of being composited first

• DRI3 1.4 syncobjs served through DRM (@ariel3259), with GPU fences published to the client's release points

• Present: vsync-off clients uncapped, and no-vsync pacing stabilised (@ariel3259)

• GLX: GetDrawableAttributes/MakeCurrent parity with Xorg, vendor names derived from the render driver (@ariel3259)

• per-device pointer acceleration profiles from desktop settings (@ariel3259)

• Mesa OML MSC rate queries (@erpalma)

• reverse-PRIME (@AprilGrimoire)

• a root source Picture now honours IncludeInferiors, so maim no longer captures just the background

• no more ghost window on the next workspace after switching (i3 + fastcompmgr)

• a correct cursor with no cursor font installed — the cursor and nil2 fonts are bundled instead of falling back to a text font

• FreeBSD VT switching fixed, and Ctrl+C no longer kills the server

• multi-GPU: the render node is resolved on split display/render SoCs, and non-desktop connectors are ignored (touchbar on M2 macbook pro)

• binary packages for aarch64 as well as x86_64

• starty launcher (startx-style: display number picking, MIT-MAGIC-COOKIE-1, session teardown)

• Present completions paced to the vblank, and the Present 1.4 acquire timeline honored (fixes free-running clients, fullscreen video, Plasma's spinner)

• keyboard layout switching: stale per-key overrides cleared and a legacy MappingNotify broadcast, so clients pick up the new layout (@azytar)

• FreeColors dispatched instead of failing with BadRequest (Tk compatibility) (@erpalma)

• GLX pbuffers, backed by a real GPU pixmap — Chrome and Steam now get GPU acceleration

• scanout buffers allocated via GBM and imported into Vulkan (wider driver/modifier coverage)

• yserver is now truly idle when nothing happens

• core-loop fairness and backpressure

• RANDR output properties, read and write (minors 12/13/14)

• RANDR output identity passthrough: EDID, EDID_DATA, ConnectorType

• RANDR fractional refresh rates from real kernel mode timings

• Xorg-compatible output names (HDMI-1, not HDMI-A-1)

• X-Resource client accounting with LocalClientPID in QueryClientIds

• per-device libinput settings (mice and touchpads) actually apply

• XI1 feedback controls, resolution control, real event selections

• pointer motion history (GetMotionEvents)

• XI2: relative RawMotion deltas, scroll-stop on finger-lift, implicit pointer grabs, unified freeze state

• XTEST cursor comparison

• RENDER: full standard PictOp family, a8-mask destinations for CompositeGlyphs, ClipByChildren parity for Composite/Glyphs/Traps/Tris

• perf: glyph rendering batched into one instanced draw per text run

• cursor recoloring, and depth-1 wire bitmaps for XCreatePixmapCursor

• XKB group state and GetMap component filtering (@AprilGrimoire)

• CopyArea source resolution simplified (@AprilGrimoire)

• stable-toolchain build fixed on Ubuntu 26.04 (@erpalma)

• Direct-only seat model (libseat dependency dropped)

• much better responsiveness on NVIDIA GPUs

• newly working apps: Steam (WebGL), ImageMagick import region-select, KDE Plasma RandR resize + ARGB popups (@erpalma), fullscreen games/video under Cinnamon

• newly tested and fixed desktops: plasma X11 (sonic DE)

• binary releases for Fedora/Debian/Ubuntu/Alpine

• FreeBSD now works

• Display hotplug now works

• xauth support, and xhost for local clients (+si:localuser:, +local:); over TCP only the cookie admits

• XINERAMA support

• RANDR gamma correction (redshift)

• direct mode VT switch

• XKB runtime layout change

• LEDs driven from XKB state

• XFIXES pointer barriers

• XC-MISC XID recycling

• musl (Alpine) build working

• newly tested and fixed desktops: bspwm/sxhkd, enlightenment 0.27, icewm, awesome, openbox, picom, blackbox

Demo

With TFP implemented, we now support compiz, demo here:

compiz-720p.mp4

Tested WMs/desktops

yserver has been tested end-to-end against the following WMs/desktops:

• Cinnamon
• MATE
• XFCE
• FVWM3
• sonic (KDE plasma X11 fork)
• wmaker
• openbox
• awesome
• picom
• compiz
• icewm
• blackbox
• bspwm/sxhkd
• i3/fastcompmgr
• enlightenment e16 + e27
• CDE (dtwm)

Hardware tested

• AMD — Ryzen 9 6900HX; i9 13900k + RX580 and RX 6800
• Intel — i5-7200U iGPU.
• NVIDIA — i5 6500 with GTX 1050 (proprietary driver).
• Snapdragon X1 X1E80100 (Adreno X1, Turnip).
• Apple M1 MBA, M2 MBP on Asahi Linux (apple-drm KMS + asahi GPU, Mesa AGX-V).
• Virtual — virtio-gpu inside virtme-ng (Venus passthrough).

FreeBSD was tested on the i9.

Installation and setup

Full instructions — dependencies per distro, device access, display manager and console startup, key bindings, troubleshooting and packaging — are in docs/setup.md, also installed to $prefix/share/doc/yserver/setup.md.

The short version, from a source checkout:

just install-local                   # builds and installs to /usr/local
sudo usermod -aG video,input $USER   # then log out and back in

Then switch to a free console and run starty. yserver drives atomic KMS directly with no seat manager, so it needs access to /dev/dri/* and /dev/input/event* and a working Vulkan driver.

Packages

• Arch (and derivatives): yserver on the AUR
• Fedora, debian, ubuntu and alpine packages in Releases (x86_64 and aarch64)

The release files are loose packages, not repositories, so install them by path:

sudo dnf install ./yserver-*.rpm
sudo apt install ./yserver_*.deb
sudo apk add --allow-untrusted ./yserver-*.apk   # signed with a per-build key

See also yserver(1) and starty(1).

macOS

yserver runs in a window on macOS 26 or later on Apple Silicon, on Mesa's KosmicKrisp Vulkan driver. Dependencies from Homebrew:

brew install mesa vulkan-loader vulkan-tools shaderc libxkbcommon fontconfig freetype pkgconf

From a source checkout:

just macos-run                 # :1, 1280x800, log in yserver-mac.log
just macos-run 2 1600x1000     # display, geometry (positional)
just macos-bundle              # builds target/yserver.app

target/yserver.app uses the Homebrew libraries and the KosmicKrisp driver from the Homebrew prefix; nothing is bundled. Started from Finder it takes the lowest free display from :1, shows it in the window title (yserver DISPLAY=:N) and logs to ~/Library/Logs/yserver.log.

--scale sets how many screen pixels one X pixel covers: auto (the default; one X pixel per point, 2 on a Retina screen), 1 (full resolution) or 2.

just macos-rootless runs it rootless instead: no desktop window, and every X top-level window becomes its own Mac window.

Text copied in X clients (CLIPBOARD) can be pasted in Mac apps, and the other way round. PRIMARY (select / middle-click) stays within X.

Clients connect with the display number, e.g. with XQuartz's clients:

DISPLAY=:1 /opt/X11/bin/xterm

Windows

yserver runs on Windows 11 (x86_64 and aarch64) and needs a GPU driver with Vulkan 1.3. Portable zips (yserver-<version>-windows-<arch>.zip) are built by CI; nothing needs installing, the C runtime and libraries are linked in. The zip's README.txt covers it in full.

Run start-yserver.cmd: it starts display :0, creates a cookie in %LOCALAPPDATA%\yserver\Xauthority on first use and prints it. Clients connect over TCP only. yserver's icon in the notification area opens Settings and quits it.

• rootless (the default): every X top-level window is its own Windows window; --rooted puts the whole X screen in one window instead
• text copied in X clients (CLIPBOARD) can be pasted in Windows apps, and the other way round
• Scale works as on macOS: auto uses 1 X pixel per screen pixel up to 125% and 2 from 150%

From WSL2 (default NAT networking):

export DISPLAY=$(ip route show default | awk '{print $3}'):0
export XAUTHORITY=/mnt/c/Users/<you>/AppData/Local/yserver/Xauthority
xterm &

ssh -X from Windows' own ssh client does not work yet (it has no xauth); use ssh -R 6010:127.0.0.1:6000 host and add the cookie for localhost:10 on the remote host.

To build it yourself, tools/windows/package.ps1 installs the C libraries with vcpkg, builds yserver and makes the zip.

Regression coverage with xts5 and rendercheck

We run the X.Org X Test Suite (xts5) against yserver to gauge protocol completeness.

Latest pass numbers per scenario live in docs/test-status.md.

To run XTS yourself, you need to install the following extra packages:

sudo pacman -S --needed autogen automake autoconf make xtrans xterm xorg-xset xorg-fonts-misc xorg-xdpyinfo xorg-bdftopcf xorg-mkfontscale xorg-util-macros

Then clone https://gitlab.freedesktop.org/xorg/test/xts.git next to the yserver repo. Build it with:

./autogen.sh
make

Switch to a free VT and use just xts-yserver-hw. It takes about 50 minutes, don't touch mouse/kb, xts drives the mouse on some tests.

Contributing

Contributions are welcome — see CONTRIBUTING.md for the toolchain, the checks CI runs, and the signed-commit requirement.

License

This project is licensed under the MIT license. Please check LICENSE.