Advanced Seminar

This is where suggestions for topics for student lectures at the EZAG are collected.

The EZAG also serves as a platform for the advanced seminar, so there are no special dates for advanced seminar presentations. In order to give a lecture as a student in the advanced seminar, you should either choose a topic from the list on this page or suggest a topic yourself. Afterwards you should contact the supervisor of the chosen topic or the chair's inbox (if you have your own topic) to determine the further course of events and a date for the lecture.

In addition to the advanced seminar presentation, an elaboration is necessary. The exact content should be discussed with the supervisor after the presentation. The elaboration should not exceed 10 pages and should be handed in to the supervisor at most 4 weeks after the advanced seminar presentation. Presentaion and elaboration are necessary to get a certificate. General information on the structure of scientific papers can be found in the section "Thesis/Diploma Structure". The basic structure should be adapted as follows: Introduction, Problem, Related Work (1 page), Core Idea, Details of an aspect, Assessment, Summary. Note: The paper should be written as continuous text (no collection of headwords !), the Duden or spell checker is strongly recommended, page numbering is also desired.

The audience of advanced seminar presentations consists of advanced students and staff. It may be useful to make some references to the OS lecture in the presentation, furthermore basic concepts should be treated as known and the introduction to the lecture can usually be compact. The focus should be on an interesting scientific topic, so that everyone can learn something.

The presentation itself should be designed for a duration of about 30 minutes, unless otherwise agreed upon. Afterwards there are usually 15 minutes for questions. It is advisable to practice the presentation before, so that you can better estimate your own speed.

For registration as the INF-AQUA module in selma, first, a registration in the INF-AQUA module must be made, then a registration for the advanced seminar must be made, and finally, a registration for the advanced seminar exam can be made.

Suggestions For Topic

Advanced Aspects of Linux

The Linux kernel is a complex codebase that features numerous specialised constructs. Its open-source nature allows for continuous refinement and innovation in system design. On the downside, this makes it hard to keep up with the ever-evolving code.

In this overarching topic you will select, research, and present one specialised Linux feature. Some examples are listed below but you are also invited to propose your own.

• Data Structures, e.g. Maple trees
• Memory Allocators (SLAB, SLOB, SLUB)
• Scheduling Algorithms, e.g. CFS (completely fair scheduler)
• Synchronisation, e.g. RCU (read-copy-update)
• Specialised User-space APIs, e.g. io_uring, eBPF
• Sub System, e.g. Crypto API, device mapper, work queues

Quellenvorschläge:

• The Linux Kernel Archives
• The Linux Kernel documentation
• What is RCU, Fundamentally?, Read-copy update: Using Execution History to Solve Concurrency Problems
• The Slab Allocator in the Linux kernel
• Ringing in a new asynchronous I/O API, The rapid growth of io_uring
• eBPF Documentation, BPF Internals
• The Device Mapper, dmsetup

Betreuer: Jan Bierbaum

State of the Art in CXL Security

Compute Express Link (CXL) is an open interconnect standard that enables high-bandwidth, low-latency communication between CPUs and devices such as accelerators and memory expanders. By tightly integrating devices into the host’s memory and cache hierarchy and allowing multiple machines to share a CXL fabric, CXL significantly extends the traditional trust boundary of a system. This architectural shift raises fundamental questions regarding isolation, confidentiality, integrity, and trust in CXL-enabled systems.

The goal of this seminar work is to provide a comprehensive overview of the current state of Compute Express Link, with a particular focus on the security mechanisms defined by the standard and the security implications of CXL-based architectures.

Specifically, the seminar work should address the following tasks:

• Overview of CXL
  Provide a brief introduction to Compute Express Link, including its motivation, core concepts, supported device types, and an overview of the CXL protocol stack and versions (CXL 1.x–3.x).

• Security Mechanisms in the CXL Standard
  Investigate and describe the security features specified by the CXL standard, with particular emphasis on:

  • CXL Integrity and Data Encryption (IDE) as introduced in CXL 2.0, including its goals, threat model, and protection scope.

  • CXL Trusted Security Protocol (TSP) in CXL 3.x, focusing on its role in supporting Trusted Execution Environments (TEEs), device authentication, and secure device management in shared fabrics.

• Related Work and Security Analysis
  Review and summarize existing research that analyzes the security of CXL-enabled systems. Discuss identified threats, attack surfaces, and proposed mitigation strategies, and relate them to the security mechanisms provided by the CXL standard.

The seminar work should critically assess whether the current security mechanisms are sufficient for the envisioned deployment scenarios of CXL, particularly in disaggregated and multi-tenant environments such as data centers.

Starting points for research include:

• CXL Consortium
• Salus: Efficient Security Support for CXL-Expanded GPU Memory

• Analyzing the security implications of the CXL.mem protocol (Bachelor Thesis)

Advisor: Matthias Hille