This is now inconsistent with pci_host_generic_core_alloc_resource(). It seems to me that you are using the rman to manage PCI bus addresses, then trying to allocate CPU addresses out of that. When those ranges do not overlap, the allocation always fails.

Trying to place physical addresses in rman has other problems, e.g., I think somewhere we assume that PCI bridge window addresses will be 32 bits, which is fine but the CPU address may be offset from that above the 4 GB limit (as with the Pi4).

I think the right thing to do is to store the PCI addresses in the rman at the time of pci_host_generic_core_alloc_resource(), and then translate them to CPU addresses only in generic_pcie_activate_resource().

Potential resolution: https://reviews.freebsd.org/D25394