Valve Ships SteamOS 3.9 Preview with Linux 7.2 and KDE 6.7.3

Valve has released the first preview build of SteamOS 3.9.0, aiming to modernize the system stack for Steam Deck, Steam Machines, and third-party handhelds that already run SteamOS 3.8. The update is notable not just for what it adds, but for how much it replaces at once—Valve swaps the Linux kernel line, jumps the desktop environment forward, and changes the Wi‑Fi backend for fresh installs. For now, SteamOS 3.8.16 remains on the Stable channel, and Valve has not set a release date for the finished rollout.

SteamOS 3.9 preview replaces kernel, desktop, and Wi‑Fi stack

In the SteamOS 3.9.0 preview, Valve switches the Linux kernel from the 6.16 LTS baseline to the current stable branch. On the desktop side, the system skips ahead by multiple KDE Plasma versions rather than updating incrementally, moving from Plasma 6.4.3 to Plasma 6.7.3. The update also includes a full replacement of the WLAN backend behavior for new installations, though existing systems will not be forced onto the new setup immediately.

Valve says the preview is for owners of a Steam Deck, a Steam Machine, and compatible handhelds from other vendors that are already running SteamOS 3.8. Moving to the preview is intended to bring newer hardware support and an updated desktop experience, but the company also acknowledges that the preview can be rough around the edges. Valve has not provided a timetable for when the Stable channel will receive SteamOS 3.9.0.

The kernel side of the change is especially significant because SteamOS 3.9 uses Linux 7.2, which Valve describes as skipping two kernel generations compared with the usual numbering—versions 7.0 and 7.1 never appeared in a preview. For most players, the day-to-day impact of filesystem and network-stack changes is unlikely to be obvious, but there is one graphics feature that stands out: preliminary HDMI 2.1 FRL support inside the AMDGPU driver. Valve notes that this is what enables 4K output at 120 Hz over HDMI, a capability that can matter more for Steam Machine owners connecting to capable TVs than for Steam Deck users, whose dock can also offer a DisplayPort output.

Valve also mentions “cache aware scheduling,” which is designed to keep related processes on the same last-level cache and can benefit CPUs with many cores and multiple cache domains. However, the practical benefit may be limited on the devices in question: the Steam Machine’s six-core CPU and the Steam Deck’s four-core CPU each only expose a single LLC, so the feature may not deliver the expected gains. Valve’s detailed release notes do not clarify whether this scheduling option is enabled in practice.

KDE Plasma 6.7.3 updates desktop features; hibernation and bootloader work continue

Alongside the kernel changes, SteamOS 3.9.0 preview brings KDE Plasma 6.7.3 into the desktop mode. Valve does not list every adjustment directly in the SteamOS notes, instead pointing to the wider Plasma 6.5, 6.6, and 6.7 announcement material. Features called out include virtual workspaces per display, a screen keyboard with a “hold” gesture for special characters, a widget to switch between light and dark appearance, and a microphone level indicator in system settings.

The desktop lock screen can also be enabled through the desktop settings for the first time, with Valve stating that it is off by default when shipped.

Valve is also continuing work on system functionality beyond the desktop. Preliminary hibernation support is present in the system but does not yet show up as an option in the gaming-mode interface. Valve frames hibernation as still being a developer-focused topic, at least for the preview stage. In the kernel, the team extended hibernation so a running process can be canceled, and it added fixes across multiple drivers. Valve also points to earlier groundwork in SteamOS 3.8.5, which prepared the Steam Deck LCD BIOS to support the feature.

On the networking front, new installs shift to wpa_supplicant rather than iwd as the WLAN backend. Valve says this should cover more networks, and it has also carried over the fast reconnect behavior that the previous backend offered after waking from sleep. Importantly, existing installations remain on iwd until the user changes the setting in the developer options; Valve lists this as a known issue.

Finally, Valve notes improvements aimed at running SteamOS on hardware it does not manufacture. The bootloader now supports additional mainboards. SteamOS can also run as a virtual machine with accelerated graphics via virtio-gpu and Venus. As part of this broader effort, Valve updates internal naming by moving scripts and packages from a “steamos-” prefix to “holo-”, the project’s internal distribution name.

Valve’s preview program currently runs three channels in parallel: Stable at 3.8.16, Beta at 3.8.26, and the Preview channel at 3.9.0. Users can change channels through the system settings and the “system update channel” option. Valve also indicates that rolling back to an older version is more involved than opting in, so the switch should be planned accordingly.

Because the preview includes a Wi‑Fi backend change for new installs, still-rough edges around hibernation visibility, and general “this may break things” uncertainty, Valve recommends that people who rely on their Steam Deck or Steam Machine as dependable gaming systems wait for the Stable release. No Stable date has been announced. Developers and testers who do try the preview are directed to report unexpected issues in the project’s GitHub issue tracker.