maccel

Mouse acceleration daemon for Linux. Brings macOS-style pointer feel to any compositor — Sway, Hyprland, Cosmic, GNOME, KDE, X11.

Status

Alpha. The core daemon works end-to-end (evdev → curve → uinput) but the macOS curve parameters are untested against real hardware and per-device tuning. See PLAN.md for the roadmap and design rationale.

Why

Linux has never matched macOS pointer feel. libinput's flat and adaptive profiles both miss the specific curve Apple uses (base linear scaling + threshold-triggered acceleration + smoothing dampening). Every prior attempt (mice, mos, libinput profile tweaks) gets close but doesn't nail it. This is one of the most-complained-about aspects of Linux desktop history.

maccel is the standalone wedge for a larger Linux desktop effort (Haven). Shipped independently because it works with any compositor, not just the parent DE.

How it works

physical mouse → /dev/input/event* (evdev)
                  │
              maccel daemon
                  │ (curve applied per-frame, magnitude-preserving)
              /dev/uinput (virtual device)
                  │
              compositor (sees maccel as the pointer)

1. Reads raw pointer events via libinput/evdev
2. Grabs the source device so the compositor doesn't see unmodified events
3. Computes per-frame velocity from event timestamps
4. Applies a configurable acceleration curve with a macos preset
5. Emits the scaled motion via a virtual uinput device
6. Forwards all other events (buttons, scroll, sync) unchanged

The daemon runs multi-device — one pipeline thread per managed pointer.

Install

Build from source

git clone https://github.com/im-tyler/maccel.git
cd maccel
cargo build --release

The binary is at target/release/maccel. See packaging/install.sh for a complete install with systemd unit + config directory:

sudo ./packaging/install.sh

Permissions

maccel needs read access to /dev/input/event* (to grab source devices) and write access to /dev/uinput (to create the virtual pointer). Two ways:

Option A — run as root (simplest): the systemd unit in packaging/maccel.service already does this.

Option B — input group + udev rule (recommended for daily use):

sudo usermod -aG input $USER
echo 'KERNEL=="uinput", GROUP="input", MODE="0660"' | sudo tee /etc/udev/rules.d/99-maccel.rules
sudo udevadm control --reload-rules
# log out and back in for the group change to take effect

Start the service

sudo systemctl enable --now maccel
sudo journalctl -u maccel -f   # tail logs

Configure

Default config lives at /etc/maccel/config.toml. Override the path via MACCEL_CONFIG=/path/to/config.toml.

[curve]
# Rough approximation of macOS pointer acceleration.
# Tuning against real hardware happens in v0.2.
base_gain = 1.0        # multiplier in the linear region (v < threshold)
threshold = 5.5        # velocity in counts/ms above which acceleration kicks in
exponent = 1.5         # curve aggressiveness above threshold

[devices]
# Empty `allow` = auto-detect all pointer devices.
# allow = ["/dev/input/event3", "/dev/input/event7"]
# deny = ["/dev/input/event0"]
allow = []
deny = []

Print the current defaults to stdout with maccel init.

CLI reference

maccel                  # run the daemon (default)
maccel run              # same as above, explicit
maccel status           # show version + default curve
maccel devices          # list detected pointer devices
maccel init             # print default TOML config
maccel profile list     # list available curve presets
maccel profile set X    # (v0.2) switch curve at runtime

Set RUST_LOG=debug (or trace) for verbose logs.

Scope

In scope:

• Pointer acceleration for mice (not touchpads)
• Multi-device support, one daemon process
• TOML config; CLI surface
• Per-device allow/deny lists
• Preset curves (macos, linear)

Out of scope (deliberate):

• Touchpad gesture handling (libinput already does this well)
• Per-application curves (deferred to Haven DE integration)
• Button remapping (use input-remapper)
• Keyboard input
• Scroll acceleration (separate problem; v0.3)

Roadmap

See PLAN.md for the full roadmap and design rationale.

• v0.1 (current) — Core daemon, evdev → curve → uinput pipeline, multi-device, systemd integration
• v0.2 — GUI config app, runtime curve switching, per-device profiles, calibration tool
• v0.3 — Scroll acceleration, additional presets, community-contributed device profiles, distribution packaging

Why this exists

This is the wedge component for a larger Linux desktop effort. macOS-refugee Linux users have no path to native-feeling pointer behavior; this is the missing piece. Shipped standalone so it works with any compositor, not just the parent DE.

License

MIT — see LICENSE.