OpenBSD 7.9, the sixtieth release of the security-focused open-source operating system, is available now. Project lead Theo de Raadt shipped the update days after his birthday, continuing the project’s twice-yearly release cadence with focused improvements to core performance, power management, and hardware support.
The release arrives as Linux has faced an unusually concentrated run of security disclosures in recent months. OpenBSD has not been touched by them. In March, Anthropic reported that its Claude Mythos model had identified a potential attack vector in OpenBSD, but further analysis revealed a denial-of-service condition rather than a breach. A malformed TCP/IP packet with bad Selective Acknowledgement options could crash the kernel, a bug traceable back 27 years. OpenBSD developers had already issued a patch two weeks before that announcement. It carries forward into 7.9.
What’s new in OpenBSD 7.9
On x86-64 hardware, OpenBSD 7.9 now supports up to 255 processor cores. A bug affecting systems with more than 512 GB of RAM is also fixed. Disk partition handling gains a higher ceiling, with the OS now supporting up to 52 partitions per disk, the limit set by the 52 letters of the Roman alphabet used as partition labels.
The CPU scheduler on x86-64 and Arm64 gains awareness of heterogeneous core designs, assigning processes to one of four performance levels: S, P, E, and L, for SMT, performance, efficient, and lethargic cores. This matters for hybrid CPU architectures that pair high-performance cores with efficiency cores, as in recent Intel and Arm chips. Basic Wi-Fi 6 support also arrives in this release, alongside the graphics driver stack from Linux kernel 6.18, LibreSSL updated to 4.3.0, OpenSSH bumped to 10.3, and multiple improvements to the Berkeley Packet Filter and the Packet Filter firewall, including source and state limiters.
Version 7.9 also brings improved support for RISC-V boards and further optimisations to the audio driver stack, already noted for its low latency. The release, as with all OpenBSD releases, ships with an original painting and a theme tune. This edition’s soundtrack is a jazz instrumental called Diamond in the Rough, composed by Bob Kitella, who works alongside de Raadt at the Alberta internet exchange YYCIX.
Power management and delayed hibernation
A new feature called delayed hibernation addresses a data safety risk that has existed in OpenBSD for some time. When a suspended laptop’s battery drops to a critical level, the system wakes itself and immediately triggers a full hibernation, writing its state to disk before powering off completely. Previously, a battery dying during suspension could leave the filesystem in a corrupted state.
This matters because OpenBSD uses FFS2, the original Berkeley Fast File System, without a journaling layer. Soft updates, a feature that once provided some protection against this kind of corruption, were removed in 2023. Delayed hibernation closes one specific failure mode for laptop users, though it does not address the broader absence of journaling.
Desktops and the installation experience
Desktop use is not OpenBSD’s primary goal, but version 7.9 ships with a full range of environments: GNOME 49, KDE Plasma 6.6, MATE 1.28, Xfce 4.20, and LXQt 2.2, alongside more minimal window managers. OpenBSD uses its own X11 server, Xenocara, based on X.org 7.7. Wayland is available for some environments with additional manual setup.
The default display manager, xenodm, cannot switch between desktop environments. Selecting Xfce instead of the default Fvwm 2.2.5 requires creating a single-line ~/.xsession file, which is workable but reflects the OS’s general philosophy: provide the tools, trust the user to configure them.
Installation on bare metal presents predictable friction. OpenBSD’s installer creates nine partitions by default, each with distinct permissions as a core part of the security model. Those sizes cannot be resized dynamically, and the text-based installer provides no guidance for customising the layout if the defaults do not suit the target machine. The installer also does not bundle Wi-Fi firmware in its 761 MB ISO. On a Lenovo ThinkPad X220, the Intel Centrino Advanced-N 6205 was detected but could not activate without the firmware. Plugging in an Ethernet cable resolved it: installation completed normally, the firmware package installed automatically, and Wi-Fi came online on first boot without any manual steps.
Testing in a VirtualBox VM revealed a related snag. Because the nine default partitions have fixed sizes, the virtual drive needs to be substantially larger than the OS’s footprint. The installer offers no help sizing things differently unless the user specifies a completely custom layout from scratch. Give it enough space, though, and the process finishes smoothly. OpenBSD also boots cleanly from a Ventoy multi-OS USB key, which simplifies getting it onto hardware alongside other operating systems.
AI code and the project’s position
A recent controversy involves tmux, the terminal multiplexer bundled with OpenBSD since 2009. The tmux project accepted some LLM-assisted code this year, including DECSET 2026 support, which means that code is now part of OpenBSD’s base system. No LLM-generated code has been committed to OpenBSD directly. De Raadt addressed the project’s position in March, citing unresolved copyright questions around AI-generated output as a primary reason for caution.
The objection from parts of the community is largely about principle rather than code quality. The specific tmux changes are small. Still, the situation may result in OpenBSD appearing on lists that flag or exclude AI-assisted software. OpenBSD 7.9 is available now for x86-64, Arm64, RISC-V, and several other architectures. Upgrade instructions and the full changelog are in the release announcement.