Comment 0 for bug 2049234

jammy kernel 5.15.0-81.90 includes the following backport:

https://github.com/torvalds/linux/commit/b0ad3c179059089d809b477a1d445c1183a7b8fe
https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/jammy/commit/?h=Ubuntu-5.15.0-91.101&id=1dcafa2582f335f0d929f3e9e736775a95271c43

This causes creation of ip6tnl tunnel interface through systemd-networkd. The following systemd commit also has to be applied to jammy:

https://github.com/systemd/systemd/commit/3be64aa462642de9fbe9f95536f8d167c19994bb

Since the systemd commit is missing on jammy, Kind=ip6tnl netdev configuration fails as follows:

> eno1: Could not create stacked netdev: Invalid argument

I believe this is a regression.

```
# eno1.network
[Match]
Name=eno1

[Network]
Tunnel=test_tun
```

```
# test_tun.netdev
[NetDev]
Name=test_tun
Kind=ip6tnl

[Tunnel]
Local=2001:db8::a
Remote=2001:db8::b
Mode=any
```

```
# test_tun.network
[Match]
Name=test_tun

[Network]
Address=10.0.0.1/24
```