Radiant 2025.2 / Linux: Fix Radiant Startup Crashes on Ubuntu 24.04

Radiant 2025.2 / Linux: Fix Radiant Startup Crashes on Ubuntu 24.04

Resolving "lsb-core Not Available" and Radiant Startup Crashes on Ubuntu 24.04 LTS

Ubuntu 24.04 LTS, codenamed Noble Numbat, represents a significant update in the Linux ecosystem, bringing modernized libraries and improved system architecture. However, with these advancements come changes that can impact compatibility with legacy software, including Lattice Radiant, a key tool for FPGA design. One common issue reported by users is the "lsb-core not available" error during Radiant startup, leading to crashes and frustration. This article addresses the root cause, explains why the error occurs, and provides actionable solutions to restore full functionality.

Understanding the "lsb-core Not Available" Error

The error message Package lsb-core is not available appears when attempting to install lsb-core via apt-get on Ubuntu 24.04. This is not a user error—it’s a reflection of a broader shift in the Linux distribution landscape. The Linux Standard Base (LSB) project has been largely deprecated in favor of more modular and lightweight package management. As a result, lsb-core is no longer included in the official Ubuntu 24.04 repositories.

This absence is not a bug in Radiant or the OS—it’s a consequence of upstream changes. The check_systemlibrary.log output confirms that the system detects the missing lsb-core package, but this is now a false positive. The script used to validate system libraries was not updated to reflect the deprecation of LSB packages, leading to misleading warnings.

Why This Happens

  • LSB is deprecated: The LSB specification has been phased out in favor of more flexible, distribution-specific package management.
  • Outdated validation scripts: The check_systemlibrary_radiant.bash script included with Radiant 2025.2 still references lsb-core, even though it’s no longer required.
  • Misleading error messages: The absence of lsb-core triggers a false alarm, causing users to believe a critical dependency is missing, when in reality, it’s not.

Fixing Radiant Startup Crashes Due to GLX and Qt Rendering Issues

While the lsb-core warning is non-critical, the actual crash at startup is often tied to graphics rendering conflicts, particularly when Radiant attempts to use OpenGL via X11. This is especially common on headless or virtualized environments, or systems with outdated or incompatible graphics drivers.

The root cause lies in how Qt, the underlying framework used by Radiant, handles rendering. By default, Qt may attempt to use GPU-accelerated rendering through GLX (OpenGL Extension to the X Window System), which can fail silently or crash on certain configurations.

Solution: Force CPU-Based Rendering

To resolve this, you need to override Qt’s default rendering behavior by setting two environment variables before launching Radiant. These variables instruct Qt to avoid GPU acceleration and instead use software rendering.

Add the following lines to your shell environment before starting Radiant:

export QT_XCB_GL_INTEGRATION=none
export QT_QUICK_BACKEND=software

These settings disable OpenGL integration with XCB (X11 Composite Extension) and force Qt Quick to render using the CPU instead of the GPU. This workaround is stable across most Ubuntu 24.04 systems, including those with limited or non-proprietary graphics drivers.

How to Apply the Fix

  1. Open a terminal.
  2. Navigate to the directory where Radiant is installed.
  3. Set the environment variables:
export QT_XCB_GL_INTEGRATION=none
export QT_QUICK_BACKEND=software
  1. Launch Radiant:
./radiant

If the application starts successfully, the fix has worked. For a permanent solution, add these exports to your shell profile (e.g., ~/.bashrc or ~/.zshrc):

echo 'export QT_XCB_GL_INTEGRATION=none' >> ~/.bashrc
echo 'export QT_QUICK_BACKEND=software' >> ~/.bashrc
source ~/.bashrc

This ensures the settings are applied every time you open a new terminal session.

Addressing the Outdated System Check Script

The check_systemlibrary.log file is designed to help users verify that all required system libraries are installed. However, in the case of Ubuntu 24.04, it incorrectly flags lsb-core as missing and potentially critical. This is a known issue with the current version of the validation script.

What You Should Know

  • lsb-core is not required for Radiant 2025.2 on Ubuntu 24.04.
  • The script is outdated and should not be relied upon as a definitive diagnostic tool.
  • The presence of lsb-core in the list of required packages is a remnant from older Ubuntu versions (e.g., 20.04 or 22.04).

Ignore the lsb-core warning in the log file. Focus instead on the actual runtime behavior. If Radiant starts and functions normally after applying the environment variable fix, the system is fully compatible.

General Best Practices for Running Radiant on Ubuntu 24.04

To ensure a smooth experience with Radiant on Ubuntu 24.04, follow these best practices:

  • Use the official installation package from Lattice Semiconductor’s website. Avoid third-party or manually compiled versions.
  • Keep your system updated with sudo apt update && sudo apt upgrade to ensure all base libraries are current.
  • Verify the presence of essential libraries such as libc6, libnss3, libjpeg-dev, and libusb-0.1-4, which are still required and correctly listed in the log.
  • Avoid installing deprecated packages like lsb-core—they are not needed and may introduce conflicts.
  • Use the environment variable workaround consistently, especially if you’re using a virtual machine, WSL, or a system with limited GPU support.

Conclusion

The "lsb-core not available" error on Ubuntu 24.04 is a symptom of outdated system validation scripts, not a real dependency issue. Radiant 2025.2 is fully compatible with Ubuntu 24.04, but requires a small configuration adjustment to avoid graphics-related crashes.

By setting QT_XCB_GL_INTEGRATION=none and QT_QUICK_BACKEND=software, you bypass the OpenGL rendering issues that cause startup failures. This solution is stable, widely tested, and recommended for all users on Ubuntu 24.04.

Remember: the absence of lsb-core is not a problem. The real fix lies in adjusting how Qt renders the interface. With these steps, you can confidently use Radiant on the latest Ubuntu LTS release without compromise.