ruv

This provides a Rust-based utility for undervolting Ryzen 5800x3d processors using the Precision Boost Overdrive (PBO) feature. It interacts with the Ryzen SMU driver to read and modify curve offsets for individual cores.

Features

• List current curve offsets for specified cores.
• Set negative curve offsets for undervolting.
• Reset all offsets to zero.
• Default action (no arguments): List current curve offsets.

Requirements

• rust and cargo.
• Root privileges are required to run the script.
• The Ryzen SMU driver (leogx9r/ryzen_smu) must be available and loaded.
• A systemd-based Linux distribution is required for the service installation.

Installation

To install the ruv utility, follow these steps:

1. Build the project:

   make

2. Install the binary, copy the systemd service file, and enable the service:

   sudo make install

   This command performs the following actions:

   • Compiles the release binary (target/release/ruv).
   • Installs the binary to /usr/local/bin/ruv.
   • Copies the ruv.service file to /etc/systemd/system/.
   • Reloads the systemd daemon (systemctl daemon-reload).
   • Enables the ruv.service to start on boot and resume (systemctl enable ruv.service).

3. To clean up the build artifacts, you can run:

   make clean

After installation, the ruv utility can be run manually. The installed ruv.service will automatically apply the offset configured in /etc/default/ruv_offset (or -20 if the file is missing/invalid) on system startup and resume from suspend by explicitly calling ruv --offset=<value>.

Uninstallation

To remove the utility and the systemd service:

sudo make uninstall

This command performs the following actions:

• Disables the ruv.service (systemctl disable ruv.service).
• Removes the service file (/etc/systemd/system/ruv.service).
• Removes the binary (/usr/local/bin/ruv).
• Reloads the systemd daemon (systemctl daemon-reload).

Usage

Run it with the following options:

• -l, --list List curve offsets
• -o, --offset=<offset> Set curve offset
• -r, --reset Reset offsets to 0
• -h, --help Print help

Default Action & Service Configuration:

If ruv is run without any arguments (--list, --offset, or --reset), its default action is now to list the current curve offsets for all cores.

The systemd service (ruv.service), however, still uses the /etc/default/ruv_offset file to apply a persistent undervolt on startup and resume.

• Create /etc/default/ruv_offset and place a single negative integer inside (e.g., -25) to specify the offset the service should apply.
• If this file does not exist, cannot be read, or contains an invalid value (not a negative integer), the service will default to applying an offset of -20.
• The service achieves this by reading the file (or using the default) and then explicitly running /usr/local/bin/ruv --offset=<value>.

Example:

sudo ruv --offset=-30

This explicitly sets a curve offset of -30 for all 8 cores.

# Run ruv without arguments
sudo ruv

This will list the current offsets for all 8 cores, as listing is the default action.

# To have the service apply -25 on boot/resume:
echo "-25" | sudo tee /etc/default/ruv_offset
# The service (installed via 'sudo make install') will read this file
# and run 'ruv --offset=-25' automatically.

Acknowledgment

This program is based on the Python version of the Ryzen undervolting utility available at svenlange2/Ryzen-5800x3d-linux-undervolting. Special thanks to the original author for their work.

Migration Note

The migration from Python to Rust was entirely made using Google Gemini 2.5 Pro, utilizing Visual Studio Code and the Roo Code plugin.