Kernkonzept switches L4Re from GPLv2 to MIT License

Dresden, September 15, 2025 - Kernkonzept GmbH, maintainer, and primary developer of the open source L4Re Operating System Framework (including the L4Re Hypervisor and L4Re Micro Hypervisor), is changing the project's license from the GNU General Public License version 2 (GPLv2) to the MIT License (Massachusetts Institute of Technology License), effective September 15, 2025.

The decision is explicitly customer- and developer-oriented: it reduces integration and compliance effort, increases project predictability, and makes it easier to use L4Re as middleware within existing, complex software stacks with heterogeneous licensing terms.

The MIT License is a permissive open-source license. It permits use, modification, and redistribution -- including in proprietary products -- provided the copyright notice and license text are retained. Unlike copyleft licenses such as GPLv2, there is no obligation to disclose one's own modifications. This simplifies approvals across Legal, Compliance, and Procurement and creates legal clarity for series production. As is standard in open source, the MIT License includes warranty and liability disclaimers.

The scope of the change covers all L4Re components controlled by Kernkonzept. Third-party components and external dependencies are excluded and remain under their respective licenses. Previously published L4Re releases under GPLv2 remain available unchanged.

To streamline contributions, Contributor License Agreements (CLAs) will be discontinued. In their place, Kernkonzept is introducing a "Signed-off-by" rule under the Developer Certificate of Origin (DCO) -- like the approach used by the Linux kernel and GCC. With the "Signed-off-by" line in the commit message, contributors confirm that they wrote the code themselves or have the necessary rights. Kernkonzept's established code review, security, and release processes remain unchanged.

"We align with our customers' practical use -- from pilot projects to series production. The MIT License reduces coordination effort, increases legal certainty, and supports stable processes. In short: more freedom, less overhead, the same rigor," says Dr. Michael Hohmuth, CEO & founder of Kernkonzept.

Dr. Adam Lackorzynski, CTO & founder, adds: "By switching to MIT, we are giving developers and integrators more freedom and increase acceptance in complex licensing environments. The key is the practical benefit: faster integration, clear compliance, and less friction in day-to-day work."

What exactly will change for customers?

* Simpler license clearance: less coordination with legal/compliance/purchasing
* Faster integration: smoother path from prototype to series production within existing platforms
* Less overhead: CLAs are discontinued, contribution and partner processes become leaner
* Predictability & quality: consistently high security and release standards through professional maintainer governance
* Compatibility: low-friction use alongside proprietary and mixed-license software

Availability and notes

* Effective date: September 15, 2025
* Repository: GitHub
* License notes and release information: to be published with release notes/tags for rollout

History: Previous L4Re releases under GPLv2 remain available.

Kernkonzept GmbH
Buchenstraße 16b
01097 Dresden
Germany

https://www.kernkonzept.com

Frau Katrin Kahle
0351 41 88 3232

katrin.kahle@kernkonzept.com

Kernkonzept is a specialist in secure virtualization and operating system technology. Our customers develop complex software products for safety- and mission-critical applications that often require certification or accreditation. Based on our open source technology L4Re - a microkernel-based operating system and hypervisor platform - we develop system solutions with a minimal attack surface, real-time capabilities and virtualization support, up to our VS GEHEIM approved product L4Re Secure Separation Kernel VS 1.0.0 and the Common Criteria EAL4+ certified L4Re Secure Separation Kernel CC 1.0.1. By using our certified and proven technology, our customers can considerably accelerate the certification of their own products - and thus significantly reduce time, costs and risk.
Our experienced operating system engineers customize these solutions to the specific requirements of the automotive, high-security and embedded markets. In addition, we support our customers with comprehensive, individual architecture consulting and development. Kernkonzept GmbH is a medium-sized company based in Dresden, Germany.

This release was published on openPR.