(In reply to EoD from comment #2)
> Are you referring to DRM_FBDEV_EMULATION?

Yes, that needs to be enabled.

> 
> │ Symbol: DRM_FBDEV_EMULATION [=n]
> │
> │ Type  : boolean
> │ Prompt: Enable legacy fbdev support for your modesetting driver
> │   Location:
> │     -> Device Drivers
> │       -> Graphics support
> │ (1)     -> Direct Rendering Manager (XFree86 4.1.0 and higher DRI support)
> (DRM[=y])
> │   Defined at drivers/gpu/drm/Kconfig:50
> │   Depends on: HAS_IOMEM [=y] && DRM [=y]
> │   Selects: DRM_KMS_HELPER [=y] && DRM_KMS_FB_HELPER [=y]