[vetinari]

With USB4 the PCIe tunneling is optional; with TB it is mandatory.

[izacus]

Ehm, the specification is clear that all external ports should expose PCIe tunneling? Or is there something that changed?

[vetinari]

I don't know what Microsoft based their claim about it (maybe their own requirements in Windows HCP?)

From the spec:

2.1.1.5 USB4 Host

Host contains:

* A Host Router.

* A USB 2.0 Host.

* An Enhanced SuperSpeed Host.

* A DisplayPort Source.

Host can also optionally contain a PCIe controller or PCIe switch.

A USB4 Host supports 20G USB4 operation (Gen 2). It optionally supports 40G USB4 operation (Gen 3) and 80G USB4 operation (Gen 4).

[izacus]

Hmm, you're right - it's Windows HCP. I found a random statement when they mandate tunneling support to "Maximize compatibility across ecosystem".

[thrwawy74]

Well that does seem short-sighted. :(