On Mon, Aug 26, 2024 at 08:27:09AM +0000, Erin_Tsao@xxxxxxxxxxx wrote: > Hi Bjorn, > Sorry for the late response. And thanks for responding to my question. > There's a few thing I would like to clarify with you. > 1. Is the physical slot number associate with the configuration of > device itself or with the configuration of device's parent? A PCIe device doesn't know its own slot number. The bridge leading to a slot (either a Root Port or a Switch Downstream Port) has the Slot Capability/Status/Control registers that manage the slot. The Slot Capabilities register contains a "Physical Slot Number". This is HwInit, which means it's set by hardware or firmware, and it's supposed to be a number that's unique within the chassis. The "Physical Slot" reported by lspci for Endpoints comes from sysfs, not from the device itself. See https://git.kernel.org/pub/scm/utils/pciutils/pciutils.git/tree/lib/sysfs.c?id=v3.13.0#n277
