One (Intel) GPU multiseat without Xephyr/Xnest, with a Xorg server per output

[Troll Berserker]

On 20/09/18 09:46, Chris Wilson wrote:
> Quoting Troll Berserker (2018-09-18 16:28:02)
>> Is it possible?
> 
> man 4 intel, search for ZaphodHeads
> -Chris

It didn't help much.
First of all, I've created an artificial seat-1 with logind (with the intel driver Xorg won't touch drm node, right?):
$ sudo loginctl attach seat-1 /sys/devices/pci0000\:00/0000\:00\:02.0/graphics/fb0

Then I've written the xorg.conf (attached)

Effect? Only one Xorg starts, at seat0, the Xorg at the seat-1 with intel driver can't get DRM master permission and unloads itself:

[  1581.001] (EE) intel(0): [drm] failed to set drm interface version: Permission denied [13].
[  1581.001] (II) intel(0): [drm] Contents of '/sys/kernel/debug/dri/0/clients':
[  1581.001] (II) intel(0): [drm]              command   pid dev master a   uid      magic
[  1581.001] (II) intel(0): [drm]                 Xorg  2404   0   y    y     0          0
[  1581.001] (II) intel(0): [drm]                 Xorg  2405   0   n    y     0          0
[  1581.001] (EE) intel(0): Failed to claim DRM device.
[  1581.002] (II) UnloadModule: "intel"

What is wrong with this xorg.conf?
-------------- next part --------------
Section "Monitor"
	Identifier "Monitor-DP1"
EndSection

Section "Device"
        Identifier "Intel0"
        MatchSeat  "seat0"
        Driver     "intel"
        BusID      "PCI:0:2:0"
        Screen     0
        Option     "AccelMethod"  "sna"
        Option     "Monitor-DP1" "DP1"
        Option     "ZaphodHeads" "0:DP1"
        Option     "TearFree" "on"
EndSection

Section "Screen"
        Identifier      "SCREEN0"
        MatchSeat       "seat0"
        Option          "AutoServerLayout" "on"
        Device          "Intel0"
        Monitor         "Monitor-DP1"
        SubSection "Display"
                Viewport 0 0
                Depth 24  
        EndSubSection
EndSection

Section "ServerLayout"
        Identifier      "LAYOUT0"
        MatchSeat       "seat0"
        Option          "AutoServerLayout" "on"
        Screen 0 "SCREEN0"
EndSection


Section "Monitor"
	Identifier "Monitor-DP2"
EndSection

Section "Device"
	Identifier "Intel1"
	MatchSeat  "seat-1"
	Driver     "intel"
	BusID      "PCI:0:2:0"
	Screen     0
	Option      "AccelMethod"  "sna"
	Option     "Monitor-DP2" "DP2"
	Option     "ZaphodHeads" "1:DP2"
	Option     "TearFree" "on"
EndSection

Section "Screen"
	Identifier	"SCREEN1"
	MatchSeat	"seat-1"
	Option		"AutoServerLayout" "on"
	Device		"Intel1"
	Monitor		"Monitor-DP2"
	SubSection "Display"
		Viewport 0 0
		Depth 24
	EndSubSection
EndSection

Section "ServerLayout"
	Identifier	"LAYOUT1"
	MatchSeat	"seat-1"
	Option		"AutoServerLayout" "on"
	Screen 0 "SCREEN1"
EndSection