On 22.03.22 12:01, Mariusz Szafrański via coreboot wrote:
At some point of time I was thinking about something called "subdomains" concept to cover this multiple root buses in one domain case so to make something like:
domain 0 //domain domain 1 //subdomain first root bus from stack x and its downstream devices end domain 2 //subdomain second root bus from stack x and its downstream devices end end domain ... ... end ...
T8he way I understood it, domains are a set of resource windows to be constrained and then distributed over children and in this case children over multiple PCI root busses. I have some doubts that subdomains map the situation correctly/efficiently, because it has essentially the same problem as knowing how to split the resources between domains correctly.
As I stated it was never implemented as subdomain level device is more a "bridge device" than "domain device"
This sounds much like my idea to have device nodes for the PCI host bridges :) I believe it's the right way to model the hierarchy. Having these nodes might also make it easier to map things to ACPI.
OTOH, does it even make sense to map this in the devicetree? The way FSP reports stacks is generated at runtime and differs depending on the hardware configuration. So having a static structure mapping that may not be interesting?
Arthur
It depends if few ms in boot time does matter.
Do you mean us? or are the HOBs that huge?
Nico