docs: users are in a bad place if they forget to note the mac address [mastering tutorial]

[gruyaume]

The mastering tutorial tells users to "Take note of access and core interfaces MAC addresses" using an ip command. The driverctl command we run shortly after will make those mac addresses inaccessible via the same ip command. If users forget to note the mac addresses here (like I did), how they can recover them is unclear.

I would suggest to either:

• Make the request to note the mac address more obviously (ex., using a warning admonition).
• Figure out how users can retrieve those mac addresses even after the driverctl command and put that in a note somewhere so that users can retrieve those.

Logs

Show ip link

ubuntu@user-plane:~$ ip link show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: enp5s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DEFAULT group default qlen 1000
    link/ether 00:16:3e:b0:be:54 brd ff:ff:ff:ff:ff:ff
3: enp6s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DEFAULT group default qlen 1000
    link/ether 00:16:3e:1b:f8:3c brd ff:ff:ff:ff:ff:ff
4: enp7s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DEFAULT group default qlen 1000
    link/ether 00:16:3e:73:d6:98 brd ff:ff:ff:ff:ff:ff

Load pci driver

ubuntu@user-plane:~$ cat << EOF | sudo tee -a /etc/rc.local
#!/bin/bash
sudo driverctl set-override 0000:07:00.0 vfio-pci
sudo driverctl set-override 0000:06:00.0 vfio-pci
EOF
sudo chmod +x /etc/rc.local
sudo /etc/rc.local
#!/bin/bash
sudo driverctl set-override 0000:07:00.0 vfio-pci
sudo driverctl set-override 0000:06:00.0 vfio-pci

Show ip link:

ubuntu@user-plane:~$ ip link show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: enp5s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DEFAULT group default qlen 1000
    link/ether 00:16:3e:b0:be:54 brd ff:ff:ff:ff:ff:ff

---

Reported from: https://canonical-charmed-aether-sd-core.readthedocs-hosted.com/en/latest/tutorials/mastering/

[Gmerold]

This problem will be gone once #95 is merged. New TF module will output the MACs for the access and the core interfaces.

Do you think that's enough to address this issue?