One kernel option broke Waydroid on SteamOS, and Valve's 3.9.3 beta puts it back
Valve has put Android binder IPC back into the SteamOS kernel, the option owners say Waydroid needs to run on a Steam Deck without unlocking the filesystem, and whose removal they reported three weeks ago. Valve's SteamOS 3.9.3 Beta note of October 16 lists "Reintroduce support for Android binder IPC" among its developer changes, and says the release is for the Beta and Preview channels, "and includes new features that are still being tested".
Galactic Racer is one of two games named in the 3.9.3 notes, for performance on resume from suspend on Steam Machine. Image: Secret Mode
Stable SteamOS is still 3.8.28, and it does not have the option. Six lines are new in 3.9.3; everything else in the note shipped in earlier 3.9 previews, including the frame-limiter fix for VR streamed to a Steam Frame that we covered in 3.9.2.
A single boolean took Waydroid with it
Binder and binderfs were compiled into the linux-neptune 6.15 and 6.16 kernels, and that is what let Waydroid run on SteamOS without modifying the root filesystem or switching off read-only mode. An owner report filed on September 28 says that in linux-neptune-618 (6.18.50, then the stable kernel) and linux-neptune-72 (7.2.4 and 7.2.7, then the beta one) the kernel configuration reads "# CONFIG_ANDROID_BINDER_IPC is not set".
The Crew Motorfest is the other, with a fix for GPU errors. Image: Ubisoft
Waydroid runs Android in a container on the same kernel rather than emulating it, which is why binder, Android's own channel between processes, has to be in the host kernel for any of it to start.
The awkward part is that the option is a boolean, so nothing can load it afterwards. In the reporter's words the only alternative is an out-of-tree binder module, which "must be rebuilt for every kernel release and taints the kernel", and what he asks Valve for instead is CONFIG_ANDROID_BINDER_IPC and CONFIG_ANDROID_BINDERFS switched back on.
He filed it against SteamOS 3.9.2 beta on a Lenovo Legion Go S, having checked both the running kernel's own configuration and the one shipped in Valve's kernel header packages.
A second report on the thread describes a persistent Waydroid install breaking on a Steam Deck on stable 3.8.28. Image: Valve
Valve's line names binder, and nothing else
The patch note does not mention Waydroid, Android apps, the config symbols or which kernel the change lands in, and issue 2848 is still open with no reply from Valve on it. The step from "Reintroduce support for Android binder IPC" to "Waydroid runs again" is the reporter's, not Valve's.
A second owner wrote on October 16 that the same removal broke a Waydroid install he had set up to live persistently on a Steam Deck on stable 3.8.28, which is the channel most owners are on. Nobody has yet posted a result from the 3.9.3 beta, so whether the restored option is enough to get Waydroid running again is still untested in public.
Steam Machine shares the SteamOS 3.9 line, and the suspend fix in this beta is written against it. Image: Valve
Two named games get fixes in the same beta
Valve also lists a performance fix for STAR WARS: Galactic Racer on resume from suspend on Steam Machine, a fix for GPU errors in The Crew Motorfest, a fix for audio dropping out when a monitor is hotplugged in a multi-monitor setup, and security and stability updates. The cumulative part of the note, which is not new, carries the Plasma 6.7.3 desktop and the move to a Linux 7.2 base.
Opting in is under Settings > System > System Update Channel, and for now that is the only way to get the kernel option back. Android on Valve hardware is moving on two tracks in the meantime, since the Steam Frame's own beta lets you right-click an .apk into your library while the Deck's kernel is still catching up to where it was in September.
