Unfortunately, there are some limitations:
- memory aperture of this controller is only 16MiB, so it is nearly unusable for graphic cards
- every attempt to generate type 1 config cycle always causes trap. These config cycles are disabled now and we don't support cards with PCIe switch.
- in some cases, attempt to do config cycle to (probably) not-yet ready card also causes trap. This cannot be detected at runtime, but it seems like very rare issue.
MFC after: 3 weeks