systemd-network-generator support for ip=NIC:dhcp,dhcp6

[dustymabe]

Component

systemd-network-generator

Is your feature request related to a problem? Please describe

When I start a system with say ip=ens7:dhcp,dhcp6 systemd-network-generator fails:

[core@cosa-devsh ~]$ cat /proc/cmdline 
BOOT_IMAGE=(hd0,gpt3)/ostree/fedora-coreos-b86cd866f732dc048ff7bf4352566511e8ffa2197730e70b23375b8e9ff43084/vmlinuz-6.3.5-200.fc38.x86_64 mitigations=auto,nosmt ignition.platform.id=qemu console=tty0 console=ttyS0,115200n8 ignition.firstboot ostree=/ostree/boot.1/fedora-coreos/b86cd866f732dc048ff7bf4352566511e8ffa2197730e70b23375b8e9ff43084/0 ip=ens7:dhcp,dhcp6
[core@cosa-devsh ~]$ 
[core@cosa-devsh ~]$ systemctl status systemd-network-generator.service 
× systemd-network-generator.service - Generate network units from Kernel command line
     Loaded: loaded (/usr/lib/systemd/system/systemd-network-generator.service; enabled; preset: enabled)
    Drop-In: /usr/lib/systemd/system/service.d
             └─10-timeout-abort.conf
     Active: failed (Result: exit-code) since Tue 2023-06-06 17:53:49 UTC; 44s ago
       Docs: man:systemd-network-generator.service(8)
    Process: 1324 ExecStart=/usr/lib/systemd/systemd-network-generator (code=exited, status=1/FAILURE)
   Main PID: 1324 (code=exited, status=1/FAILURE)
        CPU: 3ms

Jun 06 17:53:49 localhost systemd-network-generator[1324]: Failed to parse kernel command line: Invalid argument
Jun 06 17:53:49 localhost systemd[1]: systemd-network-generator.service: Main process exited, code=exited, status=1/FAILURE
Jun 06 17:53:49 localhost systemd[1]: systemd-network-generator.service: Failed with result 'exit-code'.
Jun 06 17:53:49 localhost systemd[1]: Failed to start systemd-network-generator.service - Generate network units from Kernel command line.
[core@cosa-devsh ~]$ 
[core@cosa-devsh ~]$ rpm -q systemd
systemd-253.4-1.fc38.x86_64

This syntax is supported by NetworkManager with nm-initrd-generator.

Why do I have systemd-network-generator.service enabled if I'm using NetworkManager? Because the udev pieces of systemd-network-generator.service are useful. See #27945 for a request to split out the udev functionality.

Describe the solution you'd like

Support for ip=NIC:dhcp,dhcp6 format.

Describe alternatives you've considered

No response

The systemd version you checked that didn't have the feature you are asking for

systemd-253.4-1.fc38.x86_64

[keszybz]

@yuwata could you take a look?

[mrc0mmand]

Here's a downstream BZ for completeness: https://bugzilla.redhat.com/show_bug.cgi?id=2192573