Xen Project Delivers Xen 4.21, a Modernized Hypervisor with Broader Architecture Support and Improved Performance

Xen 4.21 takes a major step towards modernized virtualization, offering greater maintainability across industries and upgraded efficiency for memory

SAN FRANCISCO, Nov. 19, 2025 /PRNewswire/ — The Xen Project, an open source hypervisor hosted at the Linux Foundation, today announced the release of Xen 4.21, which updates toolchain requirements across all architectures, improves runtime performance on x86 with smarter memory and cache handling, delivers enhanced security on Arm®-based devices, and adds early RISC-V enablement. This release marks another major modernization milestone for the Xen hypervisor, preparing the Xen Project to support automotive and embedded systems of the future.

For data center and cloud environments, Xen 4.21 delivers more efficient virtualization through smarter cache management, improved PCI handling, and a new AMD CPPC driver that provides finer-grained CPU frequency control. These updates translate to better performance per watt and improved scalability across modern multi-core servers, helping operators run more VMs with less overhead.