Ethernet device with systemd-networkd on Yocto won't work (rejects ARP replies), but does work with /etc/network/interfaces #systemd #yocto

* Ethernet device with systemd-networkd on Yocto won't work (rejects ARP replies), but does work with /etc/network/interfaces #systemd #yocto
@ 2020-09-14 18:31 eliranl
  2020-09-14 20:24 ` [yocto] " Matt Madison
  0 siblings, 1 reply; 3+ messages in thread
From: eliranl @ 2020-09-14 18:31 UTC (permalink / raw)
  To: yocto

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Hi,
(since this is a long post, i divided it to sections)

*TL;DR*

I have a networking issue in my Yocto dist; Somehow, my ethernet device won't work with systemd-networkd, but will work with /etc/network/interfaces.

*Problem*
I have an Nvidia Jetson AGX Xavier device which runs a Yocto Thud distribution based on meta-tegra's tegra-minimal-initramfs ( https://github.com/OE4T/meta-tegra/blob/master/recipes-core/images/tegra-minimal-initramfs.bb ) , which is a small initrd for Jetson Xavier, except it was modified to run with coreutils instead of busybox, and with systemd.

It has an eth0 device which is configured (with a config file in /etc/systemd/network) with a static IP address. The Xavier's Ethernet port is connected directly to another Ubuntu PC, which is also on the same subnet with a different static IP address.

I cannot get the Xavier's network device to work with systemd-networkd;

Once the device boots into the initrd, it appears as if the network device is configured correctly:

* `ifconfig` shows that eth0 is configured with the correct IP address
* The following messages appear in 'dmesg':
[   12.390612] gpio tegra-gpio wake20 for gpio=52(G:4)
[   15.242016] eqos 2490000.ether_qos eth0: Link is Up - 1Gbps/Full - flow control off

However, when I ping the Ubuntu machine on the other end of the cable, there's no response.

*Debugging*

* When running tcpdump on the Ubuntu machine, it shows that the Ubuntu machine receives an ARP request, and sends a reply back:

> 
> 20:00:55.280337 ARP, Request who-has 192.168.13.10 tell 192.168.13.6,
> length 46
> 20:00:55.280362 ARP, Reply 192.168.13.10 is-at 3c:fd:fe:81:f1:93 (oui
> Unknown), length 28
> 20:00:56.291843 ARP, Request who-has 192.168.13.10 tell 192.168.13.6,
> length 46
> 20:00:56.291866 ARP, Reply 192.168.13.10 is-at 3c:fd:fe:81:f1:93 (oui
> Unknown), length 28

* But, the arp cache on the Xavier is not updated after that; Running 'cat /proc/net/arp' on the Xavier device shows that:

> 
> 
> 
> xavier:~$ cat /proc/net/arp
> IP address       HW type     Flags       HW address            Mask    
> Device
> 192.168.13.10    0x1         0x0         00:00:00:00:00:00     *       
> eth0
> 
> 

(192.168.13.0 is the address of the machine i tried to ping. as you can see its MAC address is not updated).

* There are no iptable rules in the Xavier (according to iptables -L).
* Running 'networkctl status' on the device, shows that its State is "routable (configuring)", however i'm not sure if it's a problem or not, after searching what it means.

* I've also tried to look if I somehow installed another networking service that conflicts with systemd-networkd, but it doesn't seem like it:

> 
> 
> 
> xavier:~$ systemctl list-units|grep -i net|awk '{print $1}'
> sys-devices-2490000.ether_qos-net-eth0.device
> sys-devices-virtual-net-dummy0.device
> sys-subsystem-net-devices-dummy0.device
> sys-subsystem-net-devices-eth0.device
> systemd-resolved.service
> network-online.target
> network.target
> nss-lookup.target
> 
> 

*Using /etc/network/interface does work*

If i 'move' to using /etc/network/interfaces by doing:

1. Running: systemctl stop systemd-networkd.{socket,service}

2. Write an equivalent configuration in /etc/network/interfaces

3. Restart eth0: ifconfig eth0 down; ifconfig eth0 up

Then, all of a sudden the ping works.

*My configuration*

* In order to use systemd-networkd, I have tried various combinations of the following configuration parameters in my local.conf, after searching various resources on the internet for using systemd on Yocto:

> 
> 
> 
> DISTRO_FEATURES_append = " systemd coreutils procps"
> VIRTUAL-RUNTIME_init_manager = "systemd"
> VIRTUAL-RUNTIME_initscripts = "systemd-compat-units"
> DISTRO_FEATURES_remove = " sysvinit"
> PREFERRED_PROVIDER_udev = "systemd"
> VIRTUAL-RUNTIME_syslog = ""
> VIRTUAL-RUNTIME_login_manager = "shadow"
> #DISTRO_FEATURES_BACKFILL_CONSIDERED = "sysvinit"
> PREFERRED_PROVIDER_virtual/base-utils = "coreutils"
> VIRTUAL-RUNTIME_base-utils = "coreutils"
> DISTRO_FEATURES_remove += "wayland directfb busybox"
> VIRTUAL-RUNTIME_base-utils-syslog = ""
> PACKAGECONFIG_append_pn-systemd = "
> 
> 

And none of it seemed to work.

* The following is the non-working systemd network device configuration file:

> 
> 
> 
> [Match]
> Name=eth0
> 
> [Network]
> Address=192.168.13.6/24
> Gateway=192.168.13.10
> 
> 

* And the following is the working equivalent /etc/network/interfaces file:

> 
> 
> 
> auto eth0
> iface eth0 inet static
> address 192.168.13.6
> netmask 255.255.255.0
> 
> 

----

I also didn't find a post with similar symptoms.

Does anyone have an idea on how to debug this?

Please accept my apologies if this isn't the right forum, i wasn't sure where to sent it to.

Thanks,

Eliran

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