Comment # 16 on bug 99130 from Dorota Czaplejewicz

Here it is:

$ sudo cat /sys/kernel/debug/dri/0/i915_gem_framebuffer

fbcon size: 1024 x 768, depth 24, 32 bpp, modifier 0x0, refcount 1, obj
ffff880221116200:  p        3072KiB 41 00  uncached (pinned x 1) (display)
(ggtt offset: 00080000, size: 00300000, type: 0)