Do you need to license Thunderbolt to use it? I thought you just had to buy their transceiver chips (which just hang off a PCIe3 x4 interconnect).

You have to sign lots of NDAs and other docs, give company details, describe the product you want to develop, just to get a look at the datasheets [1]. To put that in perspective, the datasheets for their latest and greatest processors are very readily available [2]. Thunderbolt is very much an intel only game. I really wish that the PCI-SIG had gotten an open standard for external PCIe out, it would have been rather useful.

[1] https://thunderbolttechnology.net/contact/thunderbolt-develo...

[2] http://www.intel.com/content/www/us/en/processors/xeon/xeon-...

The PCIe SIG released relevant cabling ten years ago https://en.wikipedia.org/wiki/PCI_Express#PCI_Express_Extern... and noone bought it. Molex has it: http://www.molex.com/molex/products/family?key=external_pci_...

Intel is refusing to sell the chips unless you swear undying loyalty to Intel.

It's a dark ritual that involves men in robes and drinking out of Andy Grove's skull no doubt.

That's not at all anticompetitive

It's pretty terrible. You're just unable to make certain kinds of devices on what should be a super generic pci-e extender.

You do, but part of that license is validating it works and it's not cheap. It's part of the reason why thunderbolt cables are so expensive compared to their alternatives.