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x_puma_x

Member

Registered: 2010-03-20

Posts: 11

question regarding systemd/udev and PredictableNetworkInterfaceNames

Hey,

I want to enable WOL for my ethernet-card using a udev-rule and have some problems understanding udev's behaviour.
I've created the following file which works perfectly:

$ cat /etc/udev/rules.d/100-wol.rules
ACTION=="add", SUBSYSTEM=="net", KERNEL=="eth0", RUN+="/usr/bin/ethtool -s %k wol g"

But /usr/lib/udev/rules.d/80-net-name-slot.rules renames the interface to enp3s0.
So my question is:
If 80-net-name-slot.rules renames the device to enp3s0 and my rules-file is executed afterwards (starts with 100), why does the above rule work. Shouldn't this one work?:

$ cat /etc/udev/rules.d/100-wol.rules
ACTION=="add", SUBSYSTEM=="net", KERNEL=="enp3s0", RUN+="/usr/bin/ethtool -s %k wol g"

Does anyone know why the first script works instead of the second one?

65kid

Member

From: Germany

Registered: 2011-01-26

Posts: 663

Re: question regarding systemd/udev and PredictableNetworkInterfaceNames

100 comes before 80, at least in filenames...

x_puma_x

Member

Registered: 2010-03-20

Posts: 11

Re: question regarding systemd/udev and PredictableNetworkInterfaceNames

Oh. Hehe. Of course it does. *shame on me*

But the "problem" still exists after renaming 100-wol.rules to 99-wol.rules (which REALLY comes AFTER 80 )

Last edited by x_puma_x (2013-08-22 18:00:23)

WonderWoofy

Member

From: Los Gatos, CA

Registered: 2012-05-19

Posts: 8,414

Re: question regarding systemd/udev and PredictableNetworkInterfaceNames

I do it by the driver of the card rather than the kernel name.  That way, no matter what the system wants to name the thing it will be matched.  So I have:

ACTION=="add", SUBSYSTEM=="net", DRIVERS=="r8168", RUN+="/usr/bin/ethtool -s %k wol d"

x_puma_x

Member

Registered: 2010-03-20

Posts: 11

Re: question regarding systemd/udev and PredictableNetworkInterfaceNames

@WonderWoofy:
I have a working solution, too.

But i just wondered why this is the way it is :-)

$ cat /etc/udev/rules.d/99-wol.rules
ACTION=="add", SUBSYSTEM=="net", KERNEL=="e*", RUN+="/usr/bin/touch /%k"

creates the file /enp3s0

I don't understand this. Is it some kind of race-condition thing or what is it?

WonderWoofy

Member

From: Los Gatos, CA

Registered: 2012-05-19

Posts: 8,414

Re: question regarding systemd/udev and PredictableNetworkInterfaceNames

I couldn't tell you without you actually providing more information about what your system might be telling you.

x_puma_x

Member

Registered: 2010-03-20

Posts: 11

Re: question regarding systemd/udev and PredictableNetworkInterfaceNames

What info do you need? I don't really know what else to provide.

Does this help?:

$ dmesg | grep -E "enp3s0|eth0"
[    2.146664] sky2 0000:03:00.0 eth0: addr 00:23:8b:16:df:4c
[    2.430154] systemd-udevd[142]: renamed network interface eth0 to enp3s0
[    3.919376] sky2 0000:03:00.0 enp3s0: enabling interface
[    3.919453] IPv6: ADDRCONF(NETDEV_UP): enp3s0: link is not ready