Here are a couple of additional questions:

- When the network interface is created, there is no IP address
  assigned (or negotiated ?) on the Linux side. But it is done on the
  MacOS side. And in the Linux kernel logs I can also read the message:
  "ready for ThunderboltIP negotiation". Is there something missing or
  not working on the Linux side ? What is the correct way to configure
  or negotiate the IP address. For my tests I did it manually...

- When the Linux machine is started with the Thunderbolt wire already
  connected to a MacBook Pro, sometimes (but not every time) the
  network interface is not created. The Thunderbolt wire needs to be
  replugged.

FWIW you get my

Tested-by: Simon Guinot <redacted>

Simon

Simon,

Since I also performed testing on the previous patchset, I'll share what I did.

I configured Network Manager to use the TBT interface to share an internet
connection to another box.  This configures a static IP address on the local
Linux side and sets up routing.

Network manager remembers setup this in a configuration database.  
When the interface goes up it will then set up a DHCP server to hand
out an IP address to the other side.