run Xorg rootless without any input devices (or even tty?)

[Youssef GHORBAL]

Bonjour Sylvain,

	It's really work in progress for now, nothing really functional, but I'll post something when I have a functional prototype.

Youssef
-------------------
> On 9 Apr 2020, at 14:01, Sylvain Leroux <sylvain at chicoree.fr> wrote:
> 
> Bonjour Youssef,
> 
> Sorry, I don't have the answer to your quetion, but I'm interested by
> your use case. Did you document your setup somewhere?
> 
> 
> On 09/04/2020 13:35, Youssef  GHORBAL wrote:
>> Hello,
>> 
>> 	I have a special use case in an HPC environement when we want to run Xorg for 3D acceleration purposes only (basically creating GL contexts)
>> 	It's what VirtualGL[0] uses to render (server side) GL accelerated apps.
>> 
>> 	When a user is allocated a slot on an HPC compute node with a GPU card, we expect it to be able to run an Xorg (under his identity) bound to the GPU card allocated to him.
>> 		
>> 	I think the rootless Xorg topic was alread discussed elsewhere in different distrib channels (Arch, Ubuntu etc) but it was always under the assumtion that we needed a fullly featured Xorg (with displays, input devices, etc) whereas in my use case I just want an Xorg screen for GLX.
>> 
>> 	For now, I can't run Xorg without handing it a tty, so I have to preallocate a tty for a user (and manage the permissions on it) and since Xorg is not able to access input devices I have this message (but Xorg starts neverthelss):
>> 
>> 	xf86EnableIOPorts: failed to set IOPL for I/O (Operation not permitted)
>> 
>> 	My questions would be:
>> 	- Is there any way/trick to avoid allocating a tty for Xorg (and thus avoid managing tty allocations and permissions)? (maybe this does'nt make sense at all)
>> 	- Is there any way/trick to avoid Xorg to probe for any input devices at all?
>> 
>> 	Thank you for your help.
>> 
>> Youssef Ghorbal
>> 
>> [0] https://virtualgl.org/vgldoc/2_2_1/x11transport.png
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