On 14.03.2017 14:43, Zbigniew Jędrzejewski-Szmek wrote:
> On Tue, Mar 14, 2017 at 06:39:29AM +0100, poma wrote:
>> On 13.03.2017 21:37, Stephen Morris wrote:
>> [...]
>>> In fact, for me, Fedora's naming convention raises more questions than 
>>> it answers. Without knowing anything about the internal hardware design 
>>> of a motherboard, how is a usb port on a pci bus, I would expect pci 
>>> ports to be on a pci bus and usb ports to be on a usb bus, and relative 
>>> to usb ports I would expect there to be a separate bus for usb 2 and usb 
>>> 3 ports.
> 
> USB bus is a PCI device connected through the PCI bus. So the "geographical
> location" includes first the information where to find the USB bus,
> and then where to find the USB device starting from that.
> 
>> dmesg -t | grep wl -m1
>> r92su 1-3:1.0 wlp0s2f1u3: renamed from wlan0
>>
>> wlp0s2f1u3
>> wl       p0       s2        f1            u3
>> wl-wlan  p-bus=0  s-slot=2  f-function=1  u-port=3
> So this USB bus in this case is multi-function device in slot
> 2 of PCI bus 0. Different functions probably correspond to different
> USB hubs, and the wireless card happens to be connected underneath
> function 1.
> 
> I don't think you're supposed to be able to guess the name on your own.
> Rather, you have a card, and you know that it has this stable name.
> If the card dies, and you replace it with a new one (in the same
> socket), the name will not change.
> 
>> lsusb
>> Bus 001 Device 003: ...
>>
>> lsusb -t
>> /:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/6p, 480M
>>     |__ Port 3: Dev 3, If 0, Class=Vendor Specific Class, Driver=r92su, 480M
>>
>> ls /sys/devices/pci0000:00/0000:00:02.1/usb1/1-3/1-3:1.0/net/
>> wlp0s2f1u3
>>
>> lspci -d ::0c03
>> 00:02.1 USB controller: ...
>>  00    02       1
>> <bus>:<device>.<func>
>>
>> udevadm info -q env /sys/class/net/wlp0s2f1u3 | grep PATH
>> DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-3/1-3:1.0/net/wlp0s2f1u3
>> ID_NET_NAME_PATH=wlp0s2f1u3
>> ID_PATH=pci-0000:00:02.1-usb-0:3:1.0
>> ID_PATH_TAG=pci-0000_00_02_1-usb-0_3_1_0
>>
>> udevadm info -a -p /sys/class/net/wlp0s2f1u3 | grep looking -A 3
>>   looking at device 
>> '/devices/pci0000:00/0000:00:02.1/usb1/1-3/1-3:1.0/net/wlp0s2f1u3':
>>     KERNEL=="wlp0s2f1u3"
>>     SUBSYSTEM=="net"
>>     DRIVER==""
>> --
>>   looking at parent device 
>> '/devices/pci0000:00/0000:00:02.1/usb1/1-3/1-3:1.0':
>>     KERNELS=="1-3:1.0"
>>     SUBSYSTEMS=="usb"
>>     DRIVERS=="r92su"
>> --
>>   looking at parent device '/devices/pci0000:00/0000:00:02.1/usb1/1-3':
>>     KERNELS=="1-3"
>>     SUBSYSTEMS=="usb"
>>     DRIVERS=="usb"
>> --
>>   looking at parent device '/devices/pci0000:00/0000:00:02.1/usb1':
>>     KERNELS=="usb1"
>>     SUBSYSTEMS=="usb"
>>     DRIVERS=="usb"
>> --
>>   looking at parent device '/devices/pci0000:00/0000:00:02.1':
>>     KERNELS=="0000:00:02.1"
>>     SUBSYSTEMS=="pci"
>>     DRIVERS=="ehci-pci"
>> --
>>   looking at parent device '/devices/pci0000:00':
>>     KERNELS=="pci0000:00"
>>     SUBSYSTEMS==""
>>     DRIVERS==""
>>
>> Ref.
>> https://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames
>> https://github.com/systemd/systemd/blob/master/src/udev/udev-builtin-net_id.c#L46
>>  *   
>> [P<domain>]p<bus>s<slot>[f<function>][u<port>][..][c<config>][i<interface>]
>>  *                                         — USB port number chain
>>
> 
> HTH,
> Zbyszek
> 

Yeah, the emphasis is on consistency of names of network interfaces.
Thank you.
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