According to the changelog of 2.6.11-bk7:
ChangeSet@1.2009.3.162, 2005-03-10 09:09:51-08:00, adaplas@hotpop.com
[PATCH] intelfb: vesa_modes require CONFIG_FB_MODEHELPERS
The recent intelfb update made intelfb pass vesa_modes as the database to
fb_find_mode(). The array vesa_modes depends on CONFIG_FB_MODEHELPERS. Fix
Could that be it?