drmcru

drmcru is a Linux DRM/KMS custom resolution utility.

It edits monitor EDID data, exports patched EDID binaries, and can install those overrides on supported systems so the kernel exposes custom modes after reboot. Hyprland integration is included for live mode discovery, switching, verification, and generated legacy monitor=... or Hyprland 0.55+ Lua monitor rules.

drmcru is an early preview. EDID overrides affect display initialization; keep a known-good mode or another way to access the system available.

Status

This release has been tested on:

• Hyprland 0.56.0 with NVIDIA DRM
• external DisplayPort and internal eDP discovery
• Limine with limine-mkinitcpio

Exported EDIDs can be installed manually on other setups. Automatic Install/Update/Uninstall is currently limited to Limine systems that rebuild with limine-mkinitcpio or mkinitcpio presets.

Install

On Arch Linux, install drmcru-bin from the AUR using an AUR helper of your choice, for example:

yay -S drmcru-bin

Download the portable x86-64 binary from the latest release:

curl -LO https://github.com/ssupt/drmcru/releases/download/v0.1.3/drmcru-0.1.3-x86_64-unknown-linux-musl
curl -LO https://github.com/ssupt/drmcru/releases/download/v0.1.3/SHA256SUMS
sha256sum -c --ignore-missing SHA256SUMS
chmod +x drmcru-0.1.3-x86_64-unknown-linux-musl
./drmcru-0.1.3-x86_64-unknown-linux-musl doctor
./drmcru-0.1.3-x86_64-unknown-linux-musl

The TUI and manual Export work on Linux systems that expose connectors through /sys/class/drm. Hyprland is optional, but hyprctl is required for live mode discovery, switching, and verification.

Automatic Install/Update/Uninstall currently requires pkexec, Limine, mkinitcpio, and either limine-mkinitcpio or mkinitcpio presets.

Run drmcru as your normal desktop user, not with sudo. It requests only the privileged Apply/Uninstall step through pkexec; running the whole TUI as root can hide the active Hyprland session and create root-owned exports.

Build From Source

Rust 1.87 or newer is required.

git clone https://github.com/ssupt/drmcru.git
cd drmcru
cargo build --release
./target/release/drmcru doctor
./target/release/drmcru

Useful commands:

cargo run
cargo run -- demo
cargo run -- doctor
cargo run -- --help
cargo run -- --version

Run drmcru demo to explore the interface using synthetic display data without reading or changing a real monitor.

Basic Workflow

1. Select a monitor.
2. Add, edit, copy, or paste a Detailed Resolution.
3. Export the patched EDID, or Install/Update it on a supported system.
4. Reboot.
5. Run drmcru doctor.
6. If Hyprland exposes the mode, use Switch or persist the generated monitor=... rule in your Hyprland config.

Switch only selects modes already exposed by DRM/Hyprland. It does not make a new EDID mode appear.

What It Can Edit

• Established timing inspection
• Base-block detailed timing descriptors
• Base-block standard timings
• CTA-861 extension detailed timing descriptors

DisplayID Type I detailed timings are decoded and can be copied into an editable EDID DTD. DisplayID blocks themselves are currently read-only.

Detailed timings are the right place for custom modes such as 1280x1080@240. EDID standard timings have fixed aspect-ratio limits and are not suitable for arbitrary shapes.

Apply Model

Wayland compositors do not work like X11 modeline injection. For reliable custom modes, the kernel must see the mode in the connector EDID.

drmcru writes EDID overrides for use with:

drm.edid_firmware=DP-1:edid/drmcru_custom_DP-1.bin

On the supported Limine/mkinitcpio path, Install/Update modifies:

• /lib/firmware/edid/<name>.bin
• /etc/mkinitcpio.conf
• /boot/limine.conf
• /etc/limine-entry-tool.d/drmcru-edid.conf when limine-mkinitcpio is used

It writes collision-resistant .drmcru.*.bak backups before editing config and firmware files. Existing overrides for other connectors are retained in the same kernel parameter. If an install or rebuild step fails, the script restores all files changed by that run.

Recovery

If a custom mode is unusable but the desktop remains accessible, switch back to a known-good mode, choose Uninstall in drmcru, and reboot.

If the graphical session is unusable, boot once without the drm.edid_firmware=... parameter using the Limine entry editor or another boot entry. Then run drmcru, choose Uninstall, and reboot. Automatic changes to mkinitcpio.conf and limine.conf have timestamped backups beside the original files.

First-run troubleshooting

• Run drmcru doctor first and include its output when reporting a problem. It reports the drmcru and Hyprland versions, detected connectors, EDID state, and whether automatic Apply is supported.
• A newly added mode will not appear in Hyprland until the kernel boots with the EDID override. Install or manually configure the override, reboot, then Verify.
• Automatic Apply intentionally stops on unsupported bootloader/initramfs setups. Export still produces the EDID plus distribution-neutral manual instructions.
• Run the TUI in an interactive terminal (80×24 or larger is recommended). For scripts, redirected output, or support logs, use drmcru doctor instead.
• If pkexec is installed but no authentication prompt appears, make sure a polkit authentication agent is running in the desktop session.
• Internal eDP panels often cannot scale arbitrary smaller scanouts. Prefer the panel's native active resolution and change only its refresh timing.
• Use drmcru demo to check terminal rendering and controls without reading or modifying real monitor data.

Hyprland

When hyprctl is available, drmcru can:

• merge DRM connector data with hyprctl monitors -j
• list Hyprland's exposed modes
• switch to an already exposed mode
• verify the active mode
• inspect simple legacy monitor= rules and sourced config files
• inspect literal Hyprland 0.55+ hl.monitor({...}) calls
• follow literal local dofile(...) and require("hypr.monitors")-style modules

Generated persistent rules follow the detected config format: hyprland.lua takes precedence when present, otherwise hyprland.conf syntax is used. Runtime switching first tries the legacy keyword command and falls back to a Lua hl.monitor({...}) evaluation on Hyprland 0.55 and newer.

Dynamic Lua expressions are not executed during config inspection. This keeps diagnostics read-only; literal user monitor modules are followed in load order.

drmcru does not auto-edit Hyprland config.

Feedback

Use the repository's bug or hardware-report issue templates when testing a new GPU, monitor, connector, bootloader, or initramfs stack. drmcru doctor output is the most useful starting point.

License

GPL-3.0-or-later. See LICENSE.