dvb_core disabled? (warnings when compiling em28xx module)

[Tarmo Tanilsoo]

I just upgraded to Ubuntu Jaunty and to kernel 2.6.28-12-netbook-eeepc. My computer is Asus Eee 701 4G. However, when I attempted to compile drivers for my USB DTV receiver(Kworld DVB-T 380U) which makes use of em28xx_dvb module, and which used to work on Hardy and Intrepid, I get following warnings when compiling the aforementioned module:
WARNING: "dvb_dmx_init" [/home/tarmo/em28xx-new/em28xx-dvb.ko] undefined!
WARNING: "dvb_unregister_adapter" [/home/tarmo/em28xx-new/em28xx-dvb.ko] undefined!
WARNING: "dvb_register_frontend" [/home/tarmo/em28xx-new/em28xx-dvb.ko] undefined!
WARNING: "dvb_unregister_frontend" [/home/tarmo/em28xx-new/em28xx-dvb.ko] undefined!
WARNING: "dvb_net_release" [/home/tarmo/em28xx-new/em28xx-dvb.ko] undefined!
WARNING: "dvb_frontend_detach" [/home/tarmo/em28xx-new/em28xx-dvb.ko] undefined!
WARNING: "dvb_dmxdev_release" [/home/tarmo/em28xx-new/em28xx-dvb.ko] undefined!
WARNING: "dvb_dmx_swfilter" [/home/tarmo/em28xx-new/em28xx-dvb.ko] undefined!
WARNING: "dvb_net_init" [/home/tarmo/em28xx-new/em28xx-dvb.ko] undefined!
WARNING: "dvb_dmx_release" [/home/tarmo/em28xx-new/em28xx-dvb.ko] undefined!
WARNING: "dvb_register_adapter" [/home/tarmo/em28xx-new/em28xx-dvb.ko] undefined!
WARNING: "dvb_dmxdev_init" [/home/tarmo/em28xx-new/em28xx-dvb.ko] undefined!

Furthermore, freshly compiled drivers turn up unusable.

Necessary headers were installed, and headers were OK. A little google search indicated a similar case when user had custom compiled kernel without dvb-core enabled (so without CONFIG_DVB_CORE=y ).

Could it be possible that the current kernel may have been compiled with dvb_core disabled?