A compatibility shim and patched proprietary driver for FocalTech FT9366 fingerprint sensors (2808:a658) on modern Linux distributions (Arch, Fedora, NixOS).

This repository provides a working driver and a compatibility layer for FocalTech fingerprint sensors (USB ID 2808:a658), commonly found in ASUS and other modern laptops.

While the original proprietary driver was built for legacy versions of Ubuntu/Debian, this project enables it to run on modern, rolling-release distributions like Arch Linux, Fedora, and NixOS by resolving binary compatibility issues with libgusb.

• @bro2020 for https://github.com/bro2020/fprint-focaltech/tree/master
• @vladejj for https://github.com/vladejj/Debian-and-Fedora-fingerprin-setup-for-a658-sensor/tree/main

The proprietary driver binary (libfprint-2.so.2.0.0) was compiled against libgusb version 0.1.0. Modern Linux systems use libgusb 0.4.x+, which has removed several legacy functions and changed symbol versioning.

Without a fix, the fprintd service fails with the following error:

symbol lookup error: undefined symbol: g_usb_device_get_interfaces, version LIBGUSB_0.1.0

Instead of downgrading critical system libraries, this repository uses a Proxy-Shim approach:

1. Compatibility Layer: We compile a micro-library (focaltech-shim.so) that masquerades as the old LIBGUSB_0.1.0.
2. Dynamic Redirection: The shim intercepts calls from the proprietary driver and redirects them to the modern libgusb.so.2 functions already present in your system using dlsym.
3. Binary Patching: We use patchelf to inject this shim as a hard dependency into the driver binary, ensuring the system loader finds our symbols first.

Ensure you have the necessary tools for compilation and binary patching:

Arch Linux:

sudo pacman -S fprintd libfprint gcc pkgconf libgusb patchelf

The shim.c source code and shim.map provided in this repository are required.

# Compile the shim with the required version script
gcc -shared -fPIC -Wl,--version-script=shim.map -o focaltech-shim.so shim.c $(pkg-config --cflags --libs glib-2.0) -ldl

# Move the driver and shim to system library paths
sudo cp libfprint-2.so.2.0.0 /usr/lib/
sudo cp focaltech-shim.so /usr/lib/

# Inject the shim as a dependency into the proprietary driver
sudo patchelf --add-needed focaltech-shim.so /usr/lib/libfprint-2.so.2.0.0

# Install udev rules to allow fprintd to access the USB device
sudo cp 60-libfprint-2.rules /etc/udev/rules.d/
sudo udevadm control --reload-rules && sudo udevadm trigger

FocalTech sensors often fail to initialize because the Linux kernel puts them into power-saving mode too quickly. You must create a persistent udev rule to keep the sensor powered.

Create /etc/udev/rules.d/80-focaltech-fix.rules:

ACTION=="add", SUBSYSTEM=="usb", ATTR{idVendor}=="2808", ATTR{idProduct}=="a658", ATTR{power/control}="on", ATTR{power/autosuspend}="-1"

Restart the service and start the enrollment process:

sudo systemctl restart fprintd
fprintd-enroll

Pro Tip: If the command fails on the first try, keep your finger pressed firmly on the sensor before and while running the command to ensure the hardware stays awake during initialization.

• libfprint-2.so.2.0.0: The proprietary driver binary.
• shim.c: The C source code for the Proxy-Shim layer.
• shim.map: Linker script defining the LIBGUSB_0.1.0 symbol versions.
• 60-libfprint-2.rules: Hardware access rules for udev.

To use your fingerprint for sudo or login, add the following line to your /etc/pam.d/system-auth (Arch) or /etc/pam.d/common-auth (Ubuntu) file:

auth      sufficient pam_fprintd.so

Disclaimer: This driver is proprietary software owned by FocalTech/Asus. This repository is provided for interoperability purposes only. Use at your own risk.