During August 2025, Jan Gross worked on kernel-level improvements for Xen virtualization in the geerlingguy/linux and torvalds/linux repositories. He removed obsolete Xen 3.x support from the Xenbus driver, reducing maintenance overhead and aligning the codebase with current deployment environments. Jan restructured Xen PV domain detection by consolidating domain-type checks and leveraging X86_FEATURE_XENPV, which streamlined runtime logic and improved reliability for DMA buffer operations. His work, implemented in C and focused on device driver and kernel development, resulted in faster boot times and more robust virtualization workflows, demonstrating a deep understanding of system programming and modern kernel architecture requirements.