During August 2025, Jan Gross worked on kernel-level improvements for Xen virtualization in the geerlingguy/linux and torvalds/linux repositories. He focused on C programming and device driver development, removing obsolete Xen 3.x support from the Xenbus driver to streamline maintenance and better match current deployment environments. Jan reworked Xen PV domain detection by consolidating domain-type checks, leveraging X86_FEATURE_XENPV, and eliminating stale logic in gntdev, which reduced runtime overhead and improved DMA buffer reliability. His contributions enhanced system architecture by simplifying code paths and supporting faster, more reliable virtualization workflows, demonstrating depth in kernel development and system programming.