August 7, 2026 12:29 pm  

PCIe tunneling never succeeds between an Intel Titan Ridge 2C host router
and a USB4 (Thunderbolt 5) eGPU dock, although the Thunderbolt link itself
comes up fully bonded at 40 Gb/s and both routers enumerate cleanly.
tb_tunnel_pci() fails silently -- the only message is "PCIe tunnel creation
failed"

=======================================================================
HARDWARE
=======================================================================
Host : Intel NUC10i7FNH (Comet Lake, i7-10710U)
BIOS FNCML357.0067.2026.0429.1614 (04/29/2026)
Host TBT: JHL7540 Titan Ridge 2C 2018
Root port 00:1c.0 [8086:02bc] Bridges 01:00.0, 02:00.0, 02:01.0, 02:02.0 [8086:15e7] NHI 03:00.0 [8086:15e8] USB ctrl 39:00.0 [8086:15e9] Host router config space vendor/device = 0x15e78086
=> tb_switch_is_titan_ridge() == true
NVM 42.0, generation 3

Device : Minisforum DEG2 eGPU dock (OCuLink/TBT5, switch set to TBT)
Thunderbolt router: "Micro Computer (HK) Tech. Ltd. TBGAA"
vendor=0x41f device=0xd002
Router config space: USB4 Switch 8087:5786 (Revision 133, TB Version 64)
NVM 62.42, generation 4 (USB4)
GPU inside the dock: NVIDIA GTX 1060 (dock reports GPU present via LED)

After lot of test i got enough information to open a case on linux kernel mailing list and got an answer from Mika. He tried also with a TB3 laptop and a TB5 dock and got the exactly same result. His opinion is IT MUST WORK. I am waiting for further tests and maybe a patch. Stay Tuned

Regards, 

David

Hi @morgwai,

Here's the flat view of the thread on lore.kernel.org: https://lore.kernel.org/linux-usb/20260807113501.GP235112%40black.igk.intel.com/T/#u

I'm taking this one step at a time. I'm not even at the point of having a stable PCIe bridge over Thunderbolt yet, so a working NVIDIA/AMD GPU setup isn't even on my radar. But getting Intel's official Thunderbolt maintainer involved feels like the right move.

I will go and read those threads. Thx for the information. 

regards