12 Jun
2015
12 Jun
'15
6 a.m.
Hi,
On each boot, coreboot might decide to assign a different bus id to the extra roots (for example, if a device with a PCI bridge is inserted and it's bus allocation causes bus ids to shift). Technically, coreboot could even change the order extra buses are assigned bus ids, but doesn't today.
This was seen on several AMD systems - I'm told at least some Intel systems have multiple root buses, but the bus numbers are just hard wired.
This is how the qemu pxb works: root bus numbers are a config option for the root bridge device, i.e. from the guest point of view they are hard-wired.
cheers, Gerd