coreboot

It turned out that there are a lot of platforms in the tree that still don't report their fixed resources correctly. These should be added inside .read_resources of device drivers. This commit[1] provides an example how it can look like. Sometimes

• .read_resources is simply missing for a device, or
• the device driver is not considered because a PCI device ID is missing, or
• the device driver is accidentally disabled in the mainboard devicetree.

One common mistake is not to reserve the memory-mapped "BIOS" flash. Integrated resources that are handled by blobs can also be easily forgotten (at least Intel provides documentation about the complete memory map, though).

When resources are not reported, the allocator can cause conflicts with them. This can happen already by chance; chances are higher when space is tight. Also, the OS needs to be made aware of such resources or might run into the same problem (alas, this is not tied to .read_resources in coreboot but needs additional ACPI code at the moment).

[1] https://review.coreboot.org/c/coreboot/+/64077

edk2 issue has been mitigated in the default branch used by coreboot, and a patch submitted to re-enable top-down allocation by default unless upstream edk2 is used