cat /var/log/Xorg.0.log | grep DRI
[    31.390] (**) RADEON(0): Option "DRI" "3"
[    32.462] (II) glamor: EGL version 1.4 (DRI2):
[    32.582] (II) RADEON(0): [DRI2] Setup complete
[    32.582] (II) RADEON(0): [DRI2]   DRI driver: r600
[    32.582] (II) RADEON(0): [DRI2]   VDPAU driver: r600
[    32.604] (**) RADEON(0): DRI3 enabled
[    32.648] (II) GLX: Initialized DRI2 GL provider for screen 0