modetest.c from libdrm tests lists no framebuffers

Question

I wanted to play with KMS since it seems to be the preferred low-level graphics library on Linux. However, after compiling the appropriate modetest.c version (2.4.32, since that's the version of libdrm-dev I have), it shows no framebuffers when running.

$ ./modetest
trying to load module i915...success.
Encoders:
id  crtc    type    possible crtcs  possible clones 
6   4   LVDS    0x00000002  0x00000001
12  0   DAC 0x00000003  0x00000002
14  0   TVDAC   0x00000003  0x00000004

Connectors:
id  encoder status      type    size (mm)   modes   encoders
5   6   connected   LVDS    330x210     1   6
  modes:
  name refresh (Hz) hdisp hss hse htot vdisp vss vse vtot)
  1280x800 60 1280 1312 1344 1408 800 801 804 816
  props:
11  0   disconnected    VGA 0x0     0   12
13  0   disconnected    s-video 0x0     0   14

CRTCs:
id  fb  pos size
3   0   (0,0)   (0x0)
   0 0 0 0 0 0 0 0 0
4   30  (0,0)   (0x0)
  1280x800 60 1280 1312 1344 1408 800 801 804 816

Frame buffers:
id  size    pitch

$

I want to know why no frame buffers are listed.