Re: [...] "How does the new naming scheme look like, precisely?"

[poma]

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/PredictableNetworkInterfac...
> > https://github.com/systemd/systemd/blob/master/src/udev/udev-builtin-net_id....
> > [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.