After 8 months of development, the release of the free hypervisor Xen 4.19 has been published. Companies such as Amazon, Arm, EPAM Systems, and AMD participated in the development of the new release. Updates for the Xen 4.19 branch will continue until February 2026, while vulnerability fixes will be published until August 2027.
Key changes in Xen 4.19:
- Support for the FF-A Notifications asynchronous data exchange mechanism, described in the FF-A (Firmware Framework for Arm A-profile) specification, has been added for systems based on the ARM architecture. It is now possible to dynamically add and remove nodes in the Xen device tree using .dtbo files.
- For x86 architecture systems, a new x2APIC interrupt controller driver has been added, using the Cluster Logical addressing mode for internal interrupts (IPI, inter-processor interrupt) and physical addressing mode for external interrupts.
- Support for Intel Xeon Phi processors has been deprecated and will be removed in the next release.
- The PVH virtualization mode for dom0 has been reclassified as 'supported with caveats,' combining elements of paravirtualization (PV) for I/O, interrupt handling, boot organization, and hardware interaction, with full virtualization (HVM) to restrict privileged instructions, isolate system calls, and virtualize memory page tables. In PVH/HVM, support for mapping foreign pages has been added, allowing the use of QEMU stubdomain for isolation and device management in PVH mode. Optimizations have been made to speed up booting when using PVH. A new setting, XENFEAT_hvm_pirqs, allows selective enabling of pIRQ support for guest systems running in HVM mode (full virtualization).
- A new 9pfs backend has been added, allowing the use of the Plan 9 network file system for one virtual machine to access another. The new backend runs as a background process on the host environment (dom0). The backend is already in use in Xenstore-stubdom for full Xenstore tracing support.
- The maximum number of CPUs used in Xen has been increased from 4095 to 16383.
- When building with systemd (./configure --enable-systemd), the libsystemd library has been excluded from build dependencies (systemd-notify support is implemented through a custom trimmed-down library).
- For analyzing traces for AMD CPUs in xenalyze, the option "--svm-mode" is no longer needed.
- The implementation of requirements for developing safe and reliable programs in C, outlined in the MISRA-C specifications for critical systems, has continued.
- Development of ports for RISC-V and Power (ppc64le) architectures has been continued.
Source: opennet.ru
