[systemd-devel] networkd-218 seems to ignore .link files

[Tom Gundersen]

On Tue, Apr 21, 2015 at 6:26 PM, Lennart Poettering
<lennart at poettering.net> wrote:
> On Tue, 21.04.15 14:47, Tom Gundersen (teg at jklm.no) wrote:
>
>> > I'm having a similar problem while running systemd version-219. Did you work
>> > out what was wrong?
>> >
>> > My link file is ignored even when I symlink
>> > /etc/systemd/network/99-default.link to /dev/null. I don't see anything
>> > interesting in 'journalctl'.
>> >
>> > # udevadm info /sys/class/net/eth0
>> > P: /devices/pci0000:00/0000:00:04.0/0000:01:00.0/net/eth0
>> > E: DEVPATH=/devices/pci0000:00/0000:00:04.0/0000:01:00.0/net/eth0
>> > E: ID_BUS=pci
>> > E: ID_MODEL_FROM_DATABASE=RTL8111/8168/8411 PCI Express Gigabit Ethernet
>> > Contror
>> > E: ID_MODEL_ID=0x8168
>> > E: ID_NET_DRIVER=r8169
>> > E: ID_NET_NAME_MAC=enx000db936008c
>> > E: ID_NET_NAME_PATH=enp1s0
>> > E: ID_OUI_FROM_DATABASE=PC Engines GmbH
>> > E: ID_PATH=pci-0000:01:00.0
>> > E: ID_PATH_TAG=pci-0000_01_00_0
>> > E: ID_PCI_CLASS_FROM_DATABASE=Network controller
>> > E: ID_PCI_SUBCLASS_FROM_DATABASE=Ethernet controller
>> > E: ID_VENDOR_FROM_DATABASE=Realtek Semiconductor Co., Ltd.
>> > E: ID_VENDOR_ID=0x10ec
>> > E: IFINDEX=3
>> > E: INTERFACE=eth0
>> > E: SUBSYSTEM=net
>> > E: SYSTEMD_ALIAS=/sys/subsystem/net/devices/eth0
>> > E: TAGS=:systemd:
>> > E: USEC_INITIALIZED=53326
>> >
>> >
>> > # networkctl status --no-pager eth0
>> > ��● 3: eth0
>> >    Link File: n/a
>> > Network File: n/a
>> >         Type: ether
>> >        State: off (unmanaged)
>> >         Path: pci-0000:01:00.0
>> >       Driver: r8169
>> >       Vendor: Realtek Semiconductor Co., Ltd.
>> >        Model: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
>> >   HW Address: 00:0d:b9:36:00:8c (PC Engines GmbH)
>> >          MTU: 1500
>> >
>> >
>> > # cat /etc/systemd/network/01-mgmt.link
>> > [Match]
>> > Path=pci-0000:01:00.0
>> > Type=ether
>>
>> Type must be the same as what is returned in DEVTYPE=, which I guess
>> is unset for this device. So drop this and it should work.
>>
>> I see where the confusion stems from though, as we try to be helpful
>> and use a heuristic to print a Type in networkctl even when the kernel
>> does not expose a type. We probably should not do that, or allow the
>> same to be used in the .link matching logic (the heuristic is unlikely
>> to be perfect, so I hesitate a bit with the latter).
>
> What precisely is the heuristic? To assume that things are ethernet if
> not otherwise specified? Honestly, I think that's good enough, and
> probably widely accepted. If this goes wrong I am pretty sure that's
> something to fix in the driver, by simply exposing the type then...

There are two 'types', the ARP hardware identifier (link type as
exposed over rtnl) and the DEVTYPE (as exposed by libudev). The
matching logic only uses DEVTYPE. The output of networkctl (and the
udev naming to a more limited degree) uses the ARP hardware identifier
and then falls back to DEVTYPE in the case of ethernet devices to
distinguish wlan and wwan interfaces from other kinds of ethernet
interfaces.

In an ideal world, we would only use DEVTYPE and the kernel would
assign this reasonably to all devices. In the meantime we could do
some combination of DEVTYPE and ARPHRD, but the danger here is that we
will lock ourselves into some heuristic and make it impossible to
improve the kernel DEVTYPE's in the future as it would change the
behavior of current setups, which is why I have preferred to not
support any matching when DEVTYPE is not set. I'm very open to change
this if anyone has a convincing scheme in mind though.

Cheers,

Tom