The Raspberry Pi motherboard is a GPIO board. Is it at all feasible to connect a PCI board to an expansion board which is connected to the RPi's GPIO pins? Do such expansion boards exist for RPi? I assume it would not work (assumption is the lowest form of knowledge), but I have not found a definite answer on the Internet. I saw this link (Using PCI or PCIe Devices), but there are three different answers - "No", "Maybe", and "I doubt".
If you have to ask, it's beyond your ability to do it (if it's even possible, which I don't believe it is).
The Pi has some GPIO pins, and they are great for a bunch of things.
PCI, the conventional (old) PCI standard connector has two rows of 62 pins, a total of 124 pins. If you take out repetitions, that totals 124-45=79 pins (maybe imprecise).
The thing is that is probably one order of magnitude more than the number of GPIO pins the Pi has. Actually if I did the same math with the Pi that I did with the PCI, it would have 20 pins. And considering the PCI bus has to do addressing and data transfer at 33MHz, needing to generate the address bus from a GPIO would probably take much longer than the available interval.
Sure you can limit the address range (hardwire a lot of unused address pins for your application) and take out a bunch of pins, and you can make a kernel module to interface the PCI module with the GPIO, but still seems very unlikely that it would be possible.
Now if you told me you would like to interface an old 8-bit ISA board... well I did that with an Atmel 10 years ago, with a Realtek network board, and it worked just fine with an ethernet stack and all...;)