This required a runtime system (environment), which he named Eumel ("Extendable Multiuser Microprocessor ELAN-System", but also a colloquial north-German term for a likeable fool Archived 2015-09-12 at the Wayback Machine).

In 1984, he joined the Gesellschaft für Mathematik und Datenverarbeitung (GMD), the German National Research Center for Computer Science, which is now a part of the Fraunhofer Society.

However, by the early 1990s, microkernels had received a bad reputation, as systems built on top were performing poorly, culminating in the billion-dollar failure of the IBM Workplace OS.

Conceptually, the main novelty of L4 was its complete reliance on external pagers (page fault handlers), and the recursive construction of address spaces.

Liedtke also worked on computer architecture, inventing guarded page tables as a means to implement a sparsely-mapped 64-bit address space.

In the same year he joined the Thomas J. Watson Research Center, where he continued to work on L4, referred to as “Lava Nucleus” (LN) to avoid negative connotations with previously unsuccessful microkernels, such as the one used in Workplace OS.

On Sunday June 10, 2001, he died unexpectedly at Frankfurt Airport while returning from SOSP'01 program committee meeting in Chateau Lake Louise, having been ill earlier in the year and undergone two surgeries (the conference proceedings were dedicated to his memory).