PCie card information for ACPI and Device Tree systems

[Lucas Tanure]

Hi,

How can the kernel read hardware information for a PCIe card if ACPI
in the BIOS doesn't have it?
The DSDT/ACPI information doesn't contain information about an
external PCIe inserted in the motherboard, so how can the Kenerl
discover its hardware information?

If the kernel has the rule of not hardcoding hardware information in
its driver, what is the method to get hardware information for a PCIe
not part of the motherboard?

And the same question for ARM device trees. How can the driver find
hardware information about a PCIe card that is not in the loaded DTB
for the system?

Thanks
Lucas