On 02.12.2021 23:39, Ian Pilcher wrote: > I.e., how does it determine that a particular interface is an on-board > interface, and how does it determine the "number" of such an interface? > > Thanks! > It is looking at sysfs attributes (acpi_index, index and some others). Details are in src/udev/udev-builtin-net_id.c, function dev_pci_onboard().