https://bugs.freedesktop.org/show_bug.cgi?id=95017

--- Comment #16 from erhard_f@mailbox.org --- linux-4.8.3-gentoo # dmesg | grep -i agp [ 0.000000] Found U3-AGP PCI host bridge. Firmware bus number: 240->255 [ 79.271669] Linux agpgart interface v0.103 [ 79.286888] agpgart-uninorth 0000:f0:0b.0: Apple U3H chipset [ 79.300467] agpgart-uninorth 0000:f0:0b.0: configuring for size idx: 64 [ 79.308235] agpgart-uninorth 0000:f0:0b.0: AGP aperture is 256M @ 0x0 [ 82.883029] agpgart-uninorth 0000:f0:0b.0: putting AGP V3 device into 8x mode [ 82.883040] radeon 0000:f0:10.0: putting AGP V3 device into 8x mode