QEMU, a renowned software tool that allows users to emulate different computer systems, has just launched its latest version, 9.1. It comes packed with over 2800 commits contributed by 263 authors, introducing enhancements and new features to improve performance, scalability, and usability.
What’s New in QEMU 9.1?
QEMU 9.1 introduces several enhancements that improve performance, security, and compatibility. Here they are:
- Migration Features: New support for compression offload through technologies like Intelโs In-Memory Analytics Accelerator (IAA) or the User Space Accelerator Development Kit (UADK) enhances the efficiency of live migrations of virtual machines. Additionally, there is improved support for recovery from postcopy failures, enhancing the robustness of VM migrations.
- Virtio Enhancements: The update includes support for VIRTIO_F_NOTIFICATION_DATA, which allows guest drivers to send additional data when delivering device notifications. This feature is particularly useful for debugging and optimizing performance.
- Guest Agent Commands: On the guest-agent front, Linux users will find the new guest-network-get-route command useful for network management, while Windows users can benefit from new guest-ssh-* commands. There’s also expanded CLI support for configuring allowed and blocked commands, providing greater control and security.
- Security and ARM Improvements: The release patches several security vulnerabilities in the QEMU NBD server and enhances NBD TLS encryption. For ARM architecture, emulation support for several new features, increased support for nested page tables, and improved board support for multiple CPUs and peripherals are also included.
- Expanding Support Across Architectures: The LoongArch architecture now supports booting directly from an ELF kernel and running up to 256 vCPUs, alongside enhanced debugging capabilities. RISC-V updates include support for new architectural extensions and general enhancements, pushing the envelope on what can be emulated under QEMU.
- Enhanced x86 Support: For x86 architecture, there is now KVM support for running AMD SEV-SNP guests and updated CPU emulation support for newer Intel and AMD processors.
Lastly, as with any major release, some features have been retired to streamline functionality and align with modern standards. Notably, the Nios II target and several older properties and options have been removed or deprecated.
QEMU 9.1 also includes warnings about deprecated features and options, urging users to consult the “Deprecated Features” chapter of the QEMU System Emulation User’s Guide for details on replacements and future-proofing their use of the software.
The new release can be downloadedย from QEMUโs official download page, where users can find the tarball. For those interested in the specifics, visit the release announcement or check the changelog, which details a full list of changes.
