On Tuesday, October 11th, 2022 at 13:04, Christian König <ckoenig.leichtzumerken@xxxxxxxxx> wrote: > we already have quite a bunch of devices which are essentially render > only and don't expose any connectors or more general display functionality. > > Just recently I ran into a case where an older X/DDX combination > caused problems for such a device so I looked a bit into the > possibility to allow drivers to disable the primary node and only > expose the render node. > > It turned out that this effectively hides the device from X, but > OpenGL and Vulkan can still use it perfectly fine. > > The only crux is that this is checked so early in the initialization > that drivers don't have an opportunity to update their > dev->driver_features. So we will always need a separate drm_driver > structure for render only devices. Typically render-only devices still expose a primary node, but don't expose any KMS resources on it. See drmIsKMS() in libdrm. Primary nodes could still be used by older user-space for rendering with legacy DRM authentication.
