Hello,

I am setting up the wifi for a customized Linux image. It uses systemd to manage network.

Right now, I am able to config the ip address and ping 8.8.8.8, but get "bad address" when ping google.ca.

It is because that the systemd-resolved service failed to start.

systemctl status shows below info:
Active: failed (Result: exit-code)
Process: 254 ExecStart=/lib/systemd/systemd-resolved (code=exited, status=226/NAMESPACE).
Main PID: 255 (code=exited, status=226/NAMESPACE)

journalctl shows below info:
systemd-resolved.service: Failed to set up mount namespacing: /run/systemd/unit-root/dev: No such file or directory
systemd-resolved.service: Failed at step NAMESPACE spawning /lib/systemd/systemd-resolved: No such file or directory

I guess the issue is that the files required for systemd-resolved to execute successfully are not there.

But by googling I couldn't find how to set up there two files and how systemd-resolved sets up the name server.

Has tried to configure the name server in /etc/systemd/resolved.conf, /etc/systemd/resolved.conf.d/dns.conf and /run/systemd/resolve/resolv.conf. None of them works.

Any help is appreciated. Thanks!

Regards,
Crane

probably you can find here something useful. Otherwise would be nice to know a bit more about your system

Thanks Pan64 for your reply.

It is a Linux 5.15.34-v7 running on Raspberry Pi 3B. Systemd is used to manage network services.

What is your Linux distribution?

I am customizing the distribution using meta-raspberrypi Kirkstone.

Are there any error message in dmesg output?

Perhaps this article from the Arch Wiki will help.

Here's a bit that looks relevant:

dmesg shows below failure:
Failed to start Remount Root and Kernel File Systems. ->occurs once and obviously the RootFS is mounted.
Failed to start Network Name Resolution. -> multiple times
Failed to start Network Time Synchronization. -> multiple times

use systemctl to check their statues.
systemd-resolved status is failed.
systemd-timesyncd status is failed.

Wanted to try something. But, have no idea why the file /etc/systemd/network/20-wireless-dynamic.network and /etc/wpa_supplicant/wpa_supplicant-wlan0.conf are gone.
Add the files back, and even the IP address for wlan0 is not set any more.

Investigating now...

Find the typo when adding /etc/wpa_supplicant/wpa_supplicant-wlan0.conf. Fixed and get the wlan0 ip set again. Continue to address the name resolution issue.

Run resolvectl status and it shows below info:
FAiled to get global data. Failed to activate service 'org.freedesktop.resolve1': timed out (service_start_timeout=25000ms)

/etc/resolv.conf is a link file. It eventually links to /run/systemd/resolve/resolv.conf. Tried to add name server configuration in that file and it didn't work.

Wondering how to add /usr/bin/resolvconf symlink and if it make sense to add a symlink in a bin folder.

Tried to add below to configure DNS and separate lines and change port number. None of them work.
1) DNS=8.8.8.8 8.8.4.4
2) DNS=8.8.8.8:9953%wlan0 8.8.4.4:9953%wlan0
Not sure if it is really accurate. But haven't find any reference.

Basically there are two places to configure DNS server:
1) /etc/systemd/resolved.conf
2) /etc/systemd/resolved.conf.d/dns.conf
Also tried to add directly in /etc/systemd/network/20-wireless-dynamic.network.
And tried to add fallbackDNS in /etc/systemd/resolved.conf.
None of them work.
And the status of systemd-resolved is always "code-exited, status=226/NAMESPACE". Didn't find anything relevant to this error.
And the "resolvectl status" shows the error: Failed to activate service 'org.freedesktop.resolve1": timeout out.

Referred to these links:
https://gbe0.com/posts/linux/systemd-resolved-setup/
https://wiki.archlinux.org/title/systemd-resolved
and manuals for systemd-resolved.service, resolved.conf and org.freedesktop.resolve1. Some information is beyond my knowledge and didn't look deeply.
I don't think it should be this hard. Must be something missing.
Any input about ways to try or debug will be appreciated.

This looks important, but not directly related to name resolution. I think it may cause the missing /run/systemd/unit-root/dev

Thanks! It could be. Will work on that failure first to see.

systemd-remount-fs failed with these information.

root@farview-rpi3:~# systemctl status systemd-remount-fs -l
x systemd-remount-fs.service - Remount Root and Kernel File Systems
Loaded: loaded (/lib/systemd/system/systemd-remount-fs.service; enabled-runtime; vendor preset: disabled)
Active: failed (Result: exit-code) since Thu 2022-04-28 17:42:28 UTC; 25min ago
Docs: man:systemd-remount-fs.service(8)
https://www.freedesktop.org/wiki/Sof...APIFileSystems
Process: 130 ExecStart=/lib/systemd/systemd-remount-fs (code=exited, status=1/FAILURE)
Main PID: 130 (code=exited, status=1/FAILURE)

Apr 28 17:42:28 farview-rpi3 systemd[1]: Starting Remount Root and Kernel File Systems...
Apr 28 17:42:28 farview-rpi3 systemd-remount-fs[133]: mount: /dev/pts: mount point not mounted or bad option.
Apr 28 17:42:28 farview-rpi3 systemd-remount-fs[130]: /bin/mount for /dev/pts exited with exit status 32.
Apr 28 17:42:28 farview-rpi3 systemd[1]: systemd-remount-fs.service: Main process exited, code=exited, status=1/FAILURE
Apr 28 17:42:28 farview-rpi3 systemd[1]: systemd-remount-fs.service: Failed with result 'exit-code'.
Apr 28 17:42:28 farview-rpi3 systemd[1]: Failed to start Remount Root and Kernel File Systems.
root@farview-rpi3:~#

Are they possibly caused by anything missing in kernel config?

so you have problems with /dev/pts. You need to look for related error messages, probably try dmesg or journalctl.