I find the thunderbolt/usb-c hardware compatibility a mess[1]

The USB-C dock I have uses DisplayLink[2] for output its a pain to get to work 
with Linux and ~impossible on cubes without compromising security of Dom-0[3] 

As far as I know Thunderbolt Docks use DisplayPort pass-through so should just 
work assuming the thunderbolt port your using supports the feature (it may need 
to be enabled in the bios), though I haven’t used any of these so nit sure.

[1] USB (various versions), PCIe, DisplayPort and PowerDelivery all can use the 
same physical plug, and it’s very much not obvious which subset happens to work 
on any given port.
[2] proprietary compressed frame buffer over high bandwidth USB, or apparently 
also (wireless) network.
[3] you need to attach the ports usb controller directly  to Dom-0, and then 
recompile + install the binary blob Display Link driver see 
https://github.com/displaylink-rpm/displaylink-rpm , and then significant 
massaging of the Xorg configuration to get it to play nice.


Sent from my iPad

> On 13 Oct 2020, at 05:34, 'Amir Omidi' via qubes-users 
> <[email protected]> wrote:
> Did any of this ever work? I have a USB C Thunderbolt based hub and I'm 
> unable to get it to output Displayport screens.
> 
> All the USB/ethernet/etc on it work fine though.
> 
> On Thursday, January 9, 2020 at 7:54:49 AM UTC-8 [email protected] wrote:
>> 
>> 
>> On Wednesday, January 8, 2020 at 3:14:03 PM UTC-5, [email protected] wrote:
>>> 1. Qubes has pcie hotplug disabled in the dom0 kernel, which TB uses for 
>>> PCIe-based thunderbolt devices. This is disabled for security reasons.
>>> 2. The TB alternate mode that supports USBs might not instantiate the PCIe 
>>> USB controller it connects through *until a USB device is connected to that 
>>> port*.
>>> 3. Therefore...depending on BIOS support...you *might* be able to have a 
>>> USB device seen by qubes if the USB device is plugged in at power-on. Even 
>>> if that works, it might be on a USB PCIe controller that is not already 
>>> attached to your sys-usb (if you have one).
>>> 4. If it does work, you might want to create a sys-usb-c which you run only 
>>> after connecting a device to the port at boot time, and assign the (usually 
>>> hidden) PCIe USB controller that that VM only.
>>> 
>>> 
>> 
>> Thanks for the reply! I took a break in the middle of typing my own reply, 
>> for a meeting, so your message came in as I was completing it.
>> 
>> All of your points seem to line up with what I discovered poking around. 
>> Yes, I can get usb-c seen if device connected at power on.
>> 
>> Thanks for the idea of an secondary sys-usb for usb-c! I had not considered 
>> that. If I discover I really need something Usb-c, which seems likely in 
>> time, I will probably do that. For now it's really just my new yubikey, 
>> which I am going to give to someone else and replace with a USB-A/NFC.
> 
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