linux-kernel - Re: Kernel problem with multiseat on one card

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Message-ID: <AM7PR10MB39234D1B9700492A3D10DB1C8E86A@AM7PR10MB3923.EURPRD10.PROD.OUTLOOK.COM>
Date:   Mon, 4 Dec 2023 10:10:46 +0100
From:   Gert Vanhaerents <gert.vanhaerents@...mail.com>
To:     Bagas Sanjaya <bagasdotme@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux DRI Development <dri-devel@...ts.freedesktop.org>,
        Linux Nouveau <nouveau@...ts.freedesktop.org>
Cc:     Karol Herbst <kherbst@...hat.com>, Lyude Paul <lyude@...hat.com>,
        Danilo Krummrich <dakr@...hat.com>
Subject: Re: Kernel problem with multiseat on one card


Op 2/12/2023 om 14:18 schreef Bagas Sanjaya:
> On Thu, Nov 30, 2023 at 11:48:24AM +0100, Gert Vanhaerents wrote:
>> Hi Kernel list,
>> I'm the IT person of a school, earlier we used multiseatcomputers for the
>> school, i have maded with a XGL implementation and it works fine but not so
>> fantastic. The school wants that i build new computers but the XGL project
>> is too outdated so i can't use it anymore.
>>
>> How can i make a multiseatcomputer with more then one user on one card with
>> systemd? I have asked already to the makers of systemd but they said it's a
>> kernel problem.
>>
>> With Systemd loginctl and the nouveau drivers you have this:
>>
>> ─/sys/devices/pci0000:00/0000:00:03.1/0000:08:00.0/drm/card0
>>            │ [MASTER] drm:card0
>>            │
>> ├─/sys/devices/pci0000:00/0000:00:03.1/0000:08:00.0/drm/card0/card0-DVI-D-1
>>            │ │ [MASTER] drm:card0-DVI-D-1
>>            │
>> ├─/sys/devices/pci0000:00/0000:00:03.1/0000:08:00.0/drm/card0/card0-HDMI-A-1
>>            │ │ [MASTER] drm:card0-HDMI-A-1
>>            │
>> └─/sys/devices/pci0000:00/0000:00:03.1/0000:08:00.0/drm/card0/card0-VGA-1
>>            │   [MASTER] drm:card0-VGA-1
>> ├─/sys/devices/pci0000:00/0000:00:03.1/0000:08:00.0/drm/renderD128
>>            │ drm:renderD128
>> ├─/sys/devices/pci0000:00/0000:00:03.1/0000:08:00.0/graphics/fb0
>>            │ graphics:fb0 "nouveaudrmfb"
>>
>> So it will be:
>>
>> loginctl attach seat1 /sys/devices/pci0000:00/0000:00:03.1/0000:08:00.0/drm/card0/card0-VGA-1
>>
>> For the seat1 (the VGA d-sub output for seat1 and the other HDMI output for
>> seat0) and of course the mouse and keyboard.
>>
>> When you do this, all the graphics outputs are on the second seat (seat1)
>> and not anymore on the first seat. So i need to move only the VGA output to
>> seat1 and not all the outputs.
> Do you expect that GUI output is on both seats?

I want the result that i have one seat (seat0) on the VGA/D-sub output 
of the graphic card

a second seat (seat1) on the HDMI output of the graphic card

and a third seat (seat2) on the DVI output of the graphic card

In theory it should work with the following:
loginctl attach seat1 
/sys/devices/pci0000:00/0000:00:03.1/0000:08:00.0/drm/card0/card0-HDMI-A-1

loginctl attach seat2 
/sys/devices/pci0000:00/0000:00:03.1/0000:08:00.0/drm/card0/card0-DVI-D-1

But when i do this all the outputs will be used on seat2 (because they 
do all the outputs automaticly to the latest attached seat)


>>
>> When i install the proprietary Nvidia drivers, i have the following:
>>
>> [MASTER] pci:0000:08:00.0
>>            │ ├─/sys/devices/pci0000:00/0000:00:03.1/0000:08:00.0/drm/card0
>>            │ │ [MASTER] drm:card0
>>            │
>> └─/sys/devices/pci0000:00/0000:00:03.1/0000:08:00.0/drm/renderD128
>>            │   drm:renderD128
>>
>> ─/sys/devices/platform/efi-framebuffer.0/graphics/fb0
>>            │ graphics:fb0 "EFI VGA"
>>
>> So no VGA, DVI or HDMI items.
> Then report to the GitHub tracker [1].
>
> Thanks.
>
> [1]: https://github.com/NVIDIA/open-gpu-kernel-modules/issues
>