# modprobe nouveau
# DRI_PRIME=1 LIBVA_DRIVER_NAME=nouveau vainfo
error: XDG_RUNTIME_DIR not set in the environment.
error: can't connect to X server!
libva info: VA-API version 1.4.1
libva info: va_getDriverName() returns 0
libva info: User requested driver 'nouveau'
libva info: Trying to open /usr/lib/x86_64-linux-gnu/dri/nouveau_drv_video.so
libva info: Found init function __vaDriverInit_1_1
libva error: /usr/lib/x86_64-linux-gnu/dri/nouveau_drv_video.so init failed
libva info: va_openDriver() returns 2
vaInitialize failed with error code 2 (resource allocation failed),exit