CC1125: Use of GPIO0, GPIO2, GPIO3

Part Number:CC1125

I notice that on the Boosterpack-CC1125 that the above GPIO are taken out to the CC2511. They are also shown on the reference design schematics. What are these used for? If I have my own MCU to drive the CC1125 would I need these 3 pins? y the way what happened to GPIO1?

Thanks