tl;dr:
Goal:
Dual-output/single-GPU/two independent screens - a configuration called Zaphod.
Use two outputs from a system with a single graphics card or a single on-board video (integrated graphics), with a dual screen configuration so that there are two completely separate (independent) :0.0 and :0.1 screens that have nothing to do with each other; that is, the origin of each screen is (0,0).
This is known as a multi-head setup (sometimes called multiseat, or multi-seat, or dual head, or a Zaphod configuration).
One of the reasons why:
I don’t want a single screen so that; for example, dialogs that are intended to be positioned in the centre of a display always display in the middle of span across monitors in a dual-monitor configuration.
To accomplish this, you need to:
- Use two
Screensections (in the xorg.conf file) referring to the device Identifiers. For example, you can call them:Identifier "Screen0andIdentifier "Screen1" - Two
Devicesections (in the xorg.conf file) with:
Option “ZaphodHeads” “yourdevice”
(yourdevice is given by xrandr(1) tool)
Option “AccelMethod” “sna”
(In my tests, AccelMethod wasn’t needed when used withmodesetting, while it was required when used withinteldriver.) - (Only needed when used with graphics card drivers so you don’t need this step if you will use
modesettingdriver): Install the card’s driver (package names: xf86-video-*). Most xf86-video-* drivers support Zaphod mode, which allows for a single device to produce multiple X screens. For example, for a graphics card with an Intel chipset, you need to install the intel graphics driver:pkg installxf86-video-intel.
On recent FreeBSD versions, including FreeBSD 13, you would typically install drm-kmod metaport, which enables the integrated graphics chip on Intel CPUs (Intel Integrated Graphics, aka HD Graphics). With drm-kmod, X.Org autodetects the driver, and utilizes the modesetting X.Org driver and/or glamor driver.
It’s recommened to use the modesetting driver but the use of specific chipset graphics drivers is not discouraged if it’s needed.
Operating system and hardware used:
FreeBSD 13.0
csh shell
twm - Tab Window Manager for the X Window System ¹
Laptop: Lenovo ThinkPad X280 | Ultraportable 12.5” Business Laptop
External monitor: LG 29’’ Class 21:9 UltraWide FHD IPS Monitor with HDR10 (29’’ Diagonal)
% freebsd-version
13.0-RELEASE-p5
% ps $$
PID TT STAT TIME COMMAND
19567 3 Ss 0:00.09 -tcsh (tcsh)
% uname -a
FreeBSD machine1.home.arpa 13.0-RELEASE-p4 FreeBSD 13.0-RELEASE-p4
#0: Tue Aug 24 07:33:27 UTC 2021
root@amd64-builder.daemonology.net:/usr/obj/usr/src/amd64.amd64/sys/GENERIC
amd64
Note:
In code excerpts and examples, the long lines are folded and then indented to make sure they fit the page.
Two Methods of Setting Up
NOTE:
These methods have been tested on a laptop (notebook) with a dual-head Intel graphics card with two physical monitor connections.
There might be other methods available for different configurations; for example, with a dual-head Nvidia graphics cards or AMD Radeon chipsets (package name in FreeBSD: xf86-video-amdgpu).
Other possibilites include Xinerama or Xypher. ²
The two methods explained here are a static setup in xorg.conf with:
- Intel video driver - Xorg driver for Intel integrated graphics chipsets
- modesetting - video driver for framebuffer device
Each of the two drivers has its own man page: man modesetting, man intel.
Note:
You can also set up dual head dynamically by using xrandr(1) tool; however, this tool doesn’t provide support for Zaphod mode. In other words, with xrandr(1) you can quickly configure two monitors but the display is one screen, not two independent screens.
xrandr(1) tool is a command line interface to RandR (Rotate and Resize) extension ³, and can be used to set outputs for a screen dynamically, without adding any specific settings in xorg.conf.
Starting with RandR 1.2, you can set up dual head and add/remove a monitor without restarting X.
Configuration with Xorg driver for Intel Integrated Graphics Chipsets - Method 1 of 2
On FreeBSD 13, the xorg.conf is located in the
directory /usr/local/etc/X11/xorg.conf.d/. ⁴
X11 Window System Configuration
From
FreeBSD Desktop – Part 3 – X11 Window System
(Posted on May 22, 2018)
(Retrieved on Dec 12, 2021)
Historically you would create entire
/etc/X11/xorg.conffile which would include complete X11 Window System configuration.Recently to comply with FreeBSD
hier(7)directory structure and logic this can be also configured as/usr/local/etc/X11/xorg.conffile and even more recently you can just configure these parts of X11 server that you need without touching other parts.This ‘individual’ configuration is done in the
/usr/local/etc/X11/xorg.conf.ddirectory with individual files for each setting, likecard.conffor graphics card configuration.
% pciconf -lv | grep -A4 vga
vgapci0@pci0:0:2:0: class=0x030000 rev=0x07 hdr=0x00 vendor=0x8086 device=0x
5917 subvendor=0x17aa subdevice=0x2256
vendor = 'Intel Corporation'
device = 'UHD Graphics 620'
class = display
subclass = VGA
On the Lenovo x280 laptop with an external monitor plugged in:
% xrandr --listproviders
Providers: number : 1
Provider 0: id: 0x47 cap: 0xa, Sink Output,
Sink Offload crtcs: 3 outputs: 5 associated providers: 0 name:modesetting
Install the X.Org legacy driver for Intel integrated graphics chipsets (package name: xf86-video-intel).
% sudo pkg install xf86-video-intel
The content of the card.conf configuration file for graphics card configuration (in this example, I had created this file previously, customizing it for modesetting video driver). Here’s how it looked before changing it to include the X.Org legacy driver for Intel integrated graphics chipsets:
% cat /usr/local/etc/X11/xorg.conf.d/card.conf
Section "Device"
Identifier "Card0"
Driver "modesetting"
EndSection
Note:
You can designate the graphics card to work with the Intel driver by using the following Device section (but it would still be a single extended display over two monitors):
% cat /usr/local/etc/X11/xorg.conf.d/card.conf
Section "Device"
Identifier "Card0"
Driver "intel"
BusID "PCI:0:2:0"
EndSection
The value for BusID line is obtained from the first line of the output
of the command pciconf -lv | grep -A4 vga ran above.
Modify the card.conf to include the X.Org Intel legacy driver and to configure two Identifer sections (with Option set to ZaphodHeads).
% sudo vi /usr/local/etc/X11/xorg.conf.d/card.conf
Section "Device"
Identifier "Intel0"
Driver "intel"
Option "ZaphodHeads" "HDMI-2"
Option "AccelMethod" "sna"
Option "DPMS"
Screen 0
#BusID "PCI:0:2:0"
EndSection
Section "Device"
Identifier "Intel1"
Driver "intel"
Option "ZaphodHeads" "eDP-1"
Option "AccelMethod" "sna"
Option "DPMS"
Screen 1
#BusID "PCI:0:2:0"
EndSection
The BusID line is optional.
To obtain individual screen resolutions, use the randr(1) command.
On the Lenovo x280 laptop with the external monitor, LG 29’’ 21:9 UltraWide FHD IPS Monitor plugged in:
% xrandr
Screen 0: minimum 320 x 200, current 4480 x 1080, maximum 16384 x 16384
eDP-1 connected primary 1920x1080+0+0
(normal left inverted right x axis y axis) 276mm x 155mm
1920x1080 60.05*+ 60.01 59.97 59.96 59.93
---- snip ----
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
HDMI-2 connected 2560x1080+1920+0
(normal left inverted right x axis y axis) 798mm x 334mm
2560x1080 59.98*+ 74.99 50.00
---- snip ----
The dimesions (geometry), a.k.a. x resolution (horizontal resolution) and y resolution (vertical resolution) values:
for the built-in screen (on the output eDP-1): 1920x1080
for the external monitor (on the output HDMI-2): 2560x1080
|--> X
0 1920 4480
- 0 +----------------+------------------------+
| | | |
| | eDP-1 | HDMI-2 |
v | 1920x1080 | 2560x1080 |
| | |
1080 +----------------+------------------------+
|<- width=1920 ->|<- width=2560 ->|
% xdpyinfo | grep -A1 '^screen'
screen #0:
dimensions: 4480x1080 pixels (1185x285 millimeters)
Currently, two outputs form a single display (a.k.a. extended display) with the geometry (dimensions) of 4480x1080; that is, width = 4480 and height = 1080.
The goal is to modify this setup and create a dual layout X.Org configuration file with two independent outputs.
% sudo vi /usr/local/etc/X11/xorg.conf.d/layout.conf
% cat /usr/local/etc/X11/xorg.conf.d/layout.conf
Section "ServerLayout"
Identifier "DualHeadConf"
Screen 0 "Screen0" 1920 0
Screen 1 "Screen1" 0 0
EndSection
For the Intel driver kernel module to be loaded at startup in the boot process you need to add this line in /etc/rc.conf:
kld_list="i915kms"
Note:
In previous FreeBSD releases, you would need to add a line kern.vty=vt to /boot/loader.conf but that’s not needed anymore as this is the default in new FreeBSD releases.
Resource:
FreeBSD Handbook - Chapter 5. The X Window System - 5.4.3. Kernel Mode Setting (KMS)
(Retrieved on Dec 12, 2021)
When the computer switches from displaying the console to a higher screen resolution for X, it must set the video output mode. Recent versions of Xorg use a system inside the kernel to do these mode changes more efficiently. Older versions of FreeBSD use sc(4), which is not aware of the KMS system. The end result is that after closing X, the system console is blank, even though it is still working. The newer vt(4) console avoids this problem.
Add this line to /boot/loader.conf to enable vt(4):
kern.vty=vt
Find out Modeline values for the output eDP-1 (the built-in laptop screen).
% grep -i modeline /var/log/Xorg.0.log | wc -l
68
Note:
Instead of obtaining Modeline values from Xorg log file, you can use cvt(1) (a utility for calculating VESA Coordinated Video Timing modes) or gtf(1) (a utility for calculating VESA GTF modes).
See examples below; immediately after the section showing how to obtain Modeline values from the Xorg log file.
% grep -n 'Printing probed modes for output eDP-1' /var/log/Xorg.0.log
179:[ 106.950] (II) intel(0): Printing probed modes for output eDP-1
% sed -n 179,211p Xorg.0.log | wc -l
33
Filtering out for the highest refresh rate, which for this output is 60 Hz:
% sed -n 179,211p Xorg.0.log | grep x60 | wc -l
10
% sed -n 179,211p Xorg.0.log | grep x60 | grep '1920x1080' | wc -l
2
Note:
The long lines are folded and then indented to make sure they fit the page.
% sed -n 179,211p Xorg.0.log | grep x60 | grep '1920x1080'
[ 106.950] (II) intel(0): Modeline "1920x1080"x60.0
141.00 1920 1936 1952 2104 1080 1083 1097 1116 -hsync -vsync (67.0 kHz eP)
[ 106.950] (II) intel(0): Modeline "1920x1080"x60.0
173.00 1920 2048 2248 2576 1080 1083 1088 1120 -hsync +vsync (67.2 kHz d)
Similarly, find out Modeline values for the output HDMI-2
(the external 29’’ LG monitor).
% grep -n 'Printing probed modes for output HDMI-2' /var/log/Xorg.0.log
285:[ 107.364] (II) intel(0): Printing probed modes for output HDMI-2
% sed -n 285,319p /var/log/Xorg.0.log | wc -l
35
Filtering out for the highest refresh rate, which for this output is 75 Hz:
% sed -n 285,319p /var/log/Xorg.0.log | grep x75 | wc -l
7
% sed -n 285,319p /var/log/Xorg.0.log | grep x75 | grep '2560x1080' | wc -l
1
% sed -n 285,319p /var/log/Xorg.0.log | grep x75 | grep '2560x1080'
[ 107.364] (II) intel(0): Modeline "2560x1080"x75.0
228.25 2560 2608 2640 2720 1080 1083 1093 1119 +hsync -vsync (83.9 kHz e)
If you wanted to calculate Modeline values with cvt(1) (usage: cvt [-v|--verbose] [-r|--reduced] h-resolution v-resolution [refresh]), where --verbose is “Warn verbosely when a given mode does not completely correspond with CVT standards”, or with gtf(1) (usage: gtf x y refresh [-v|--verbose] [-f|--fbmode] [-x|--xorgmode]), where --verbose is: “Enable verbose printouts This shows a trace for each step of the computation”.
For both cvt(1) and gtf(1): x : the desired horizontal resolution; y : the desired vertical resolution; refresh : the desired refresh rate.
% cvt --verbose 1920 1080 60
# 1920x1080 59.96 Hz (CVT 2.07M9) hsync: 67.16 kHz; pclk: 173.00 MHz
Modeline "1920x1080_60.00"
173.00 1920 2048 2248 2576 1080 1083 1088 1120 -hsync +vsync
% cvt --verbose 2560 1080 75
Warning: Aspect Ratio is not CVT standard.
# 2560x1080 74.94 Hz (CVT) hsync: 84.68 kHz; pclk: 294.00 MHz
Modeline "2560x1080_75.00"
294.00 2560 2744 3016 3472 1080 1083 1093 1130 -hsync +vsync
% gtf 1920 1080 60 --verbose
1: [H PIXELS RND] : 1920.000000
2: [V LINES RND] : 1080.000000
3: [V FIELD RATE RQD] : 60.000000
4: [TOP MARGIN (LINES)] : 0.000000
5: [BOT MARGIN (LINES)] : 0.000000
6: [INTERLACE] : 0.000000
7: [H PERIOD EST] : 14.909035
8: [V SYNC+BP] : 37.000000
9: [V BACK PORCH] : 34.000000
10: [TOTAL V LINES] : 1118.000000
11: [V FIELD RATE EST] : 59.994118
12: [H PERIOD] : 14.907574
13: [V FIELD RATE] : 59.999996
14: [V FRAME RATE] : 59.999996
15: [LEFT MARGIN (PIXELS)] : 0.000000
16: [RIGHT MARGIN (PIXELS)] : 0.000000
17: [TOTAL ACTIVE PIXELS] : 1920.000000
18: [IDEAL DUTY CYCLE] : 25.527727
19: [H BLANK (PIXELS)] : 656.000000
20: [TOTAL PIXELS] : 2576.000000
21: [PIXEL FREQ] : 172.798065
22: [H FREQ] : 67.079994
17: [H SYNC (PIXELS)] : 208.000000
18: [H FRONT PORCH (PIXELS)] : 120.000000
36: [V ODD FRONT PORCH(LINES)] : 1.000000
# 1920x1080 @ 60.00 Hz (GTF) hsync: 67.08 kHz; pclk: 172.80 MHz
Modeline "1920x1080_60.00"
172.80 1920 2040 2248 2576 1080 1081 1084 1118 -HSync +Vsync
% gtf 2560 1080 75 --verbose
1: [H PIXELS RND] : 2560.000000
2: [V LINES RND] : 1080.000000
3: [V FIELD RATE RQD] : 75.000000
4: [TOP MARGIN (LINES)] : 0.000000
5: [BOT MARGIN (LINES)] : 0.000000
6: [INTERLACE] : 0.000000
7: [H PERIOD EST] : 11.825470
8: [V SYNC+BP] : 47.000000
9: [V BACK PORCH] : 44.000000
10: [TOTAL V LINES] : 1128.000000
11: [V FIELD RATE EST] : 74.967407
12: [H PERIOD] : 11.820331
13: [V FIELD RATE] : 75.000000
14: [V FRAME RATE] : 75.000000
15: [LEFT MARGIN (PIXELS)] : 0.000000
16: [RIGHT MARGIN (PIXELS)] : 0.000000
17: [TOTAL ACTIVE PIXELS] : 2560.000000
18: [IDEAL DUTY CYCLE] : 26.453901
19: [H BLANK (PIXELS)] : 928.000000
20: [TOTAL PIXELS] : 3488.000000
21: [PIXEL FREQ] : 295.084808
22: [H FREQ] : 84.600006
17: [H SYNC (PIXELS)] : 280.000000
18: [H FRONT PORCH (PIXELS)] : 184.000000
36: [V ODD FRONT PORCH(LINES)] : 1.000000
# 2560x1080 @ 75.00 Hz (GTF) hsync: 84.60 kHz; pclk: 295.08 MHz
Modeline "2560x1080_75.00"
295.08 2560 2744 3024 3488 1080 1081 1084 1128 -HSync +Vsync
Create Monitor sections and a Screen section.
% sudo vi /usr/local/etc/X11/xorg.conf.d/monitors.conf
% cat /usr/local/etc/X11/xorg.conf.d/monitors.conf
Section "Monitor"
Identifier "eDP-1"
Modeline "1920x1080x60.00" 141.00 1920 1936 1952 2104 1080 1083 1097 1116 -hsync -vsync
Option "DPMS" "true" # DPMS (Display Power Management Signaling)
EndSection
Section "Monitor"
Identifier "HDMI-2"
Modeline "2560x1080x75.00" 228.25 2560 2608 2640 2720 1080 1083 1093 1119 +hsync -vsync
Option "DPMS" "true" # DPMS (Display Power Management Signaling)
EndSection
# A Screen section ties a device (video card) to a monitor at a specific
# colour depth and set of display resolutions.
Section "Screen"
Identifier "Screen0"
Monitor "HDMI-2"
DefaultDepth 24
Device "Intel0"
SubSection "Display"
Modes "2560x1080x75.00"
Viewport 1920 0
Depth 24
EndSubSection
EndSection
Section "Screen"
Identifier "Screen1"
Monitor "eDP-1"
DefaultDepth 24
Device "Intel1"
SubSection "Display"
Modes "1920x1080x60.00"
Viewport 0 0
Depth 24
EndSubSection
EndSection
The whole xorg.conf file:
% cat /usr/local/etc/X11/xorg.conf.d/card.conf; printf %s\\n; \
cat /usr/local/etc/X11/xorg.conf.d/fonts.conf; printf %s\\n; \
cat /usr/local/etc/X11/xorg.conf.d/keyboard.conf; printf %s\\n; \
cat /usr/local/etc/X11/xorg.conf.d/layout.conf; printf %s\\n; \
cat /usr/local/etc/X11/xorg.conf.d/modules.conf; printf %s\\n; \
cat /usr/local/etc/X11/xorg.conf.d/monitors.conf
Section "Device"
Identifier "Intel0"
Driver "intel"
Option "ZaphodHeads" "HDMI-2"
Option "AccelMethod" "sna"
Option "DPMS"
Screen 0
#BusID "PCI:0:2:0"
EndSection
Section "Device"
Identifier "Intel1"
Driver "intel"
Option "ZaphodHeads" "eDP-1"
Option "AccelMethod" "sna"
Option "DPMS"
Screen 1
#BusID "PCI:0:2:0"
EndSection
Section "Files"
FontPath "/usr/local/share/fonts/dejavu/"
EndSection
Section "InputClass"
Identifier "All Keyboards"
MatchIsKeyboard "yes"
Option "XkbLayout" "us, rs(latinunicode), rs"
Option "XkbOptions" "ctrl:nocaps,grp:rctrl_toggle"
EndSection
Section "ServerLayout"
Identifier "DualHeadConf"
Screen 0 "Screen0" 1920 0
Screen 1 "Screen1" 0 0
EndSection
Section "Module"
Load "freetype"
EndSection
Section "Monitor"
Identifier "eDP-1"
Modeline "1920x1080x60.00" 141.00 1920 1936 1952 2104 1080 1083 1097 1116 -hsync -vsync
Option "DPMS" "true" # DPMS (Display Power Management Signaling)
EndSection
Section "Monitor"
Identifier "HDMI-2"
Modeline "2560x1080x75.00" 228.25 2560 2608 2640 2720 1080 1083 1093 1119 +hsync -vsync
Option "DPMS" "true" # DPMS (Display Power Management Signaling)
EndSection
# A Screen section ties a device (video card) to a monitor at a specific
# colour depth and set of display resolutions.
Section "Screen"
Identifier "Screen0"
Monitor "HDMI-2"
DefaultDepth 24
Device "Intel0"
SubSection "Display"
Modes "2560x1080x75.00"
Viewport 1920 0
Depth 24
EndSubSection
EndSection
Section "Screen"
Identifier "Screen1"
Monitor "eDP-1"
DefaultDepth 24
Device "Intel1"
SubSection "Display"
Modes "1920x1080x60.00"
Viewport 0 0
Depth 24
EndSubSection
EndSection
Restart Xorg.
% pkill Xorg
After restarting Xorg:
% xdpyinfo | grep -A1 '^screen'
screen #0:
dimensions: 2560x1080 pixels (677x285 millimeters)
--
screen #1:
dimensions: 1920x1080 pixels (508x285 millimeters)
On the external monitor (output: HDMI-2):
% xrandr --listproviders
Providers: number : 1
Provider 0: id: 0x43 cap: 0xb, Source Output, Sink Output,
Sink Offload crtcs: 2 outputs: 2 associated providers: 0 name:Intel
% xrandr
Screen 0: minimum 8 x 8, current 2560 x 1080, maximum 32767 x 32767
HDMI-2 connected primary 2560x1080+0+0
(normal left inverted right x axis y axis) 800mm x 340mm
2560x1080x75.00 74.99*+
2560x1080 59.98 + 74.99 50.00
3840x2160 30.00 25.00 24.00 29.97 23.98
2560x1440 59.95
1920x1080 74.99 60.00 50.00 59.94
1680x1050 59.88
1600x900 60.00
1280x1024 75.02 60.02
1280x800 59.91
1152x864 75.00 59.97
1280x720 60.00 50.00 59.94
1024x768 75.03 60.00
1024x576 59.97
832x624 74.55
800x600 75.00 60.32
720x576 50.00
720x480 60.00 59.94
640x480 75.00 60.00 59.94
VIRTUAL1 disconnected (normal left inverted right x axis y axis)
On the laptop built-in screen (output: eDP-1):
% xrandr --listproviders
Providers: number : 1
Provider 0: id: 0xcc cap: 0xb, Source Output, Sink Output,
Sink Offload crtcs: 2 outputs: 2 associated providers: 0 name:Intel
% xrandr
Screen 1: minimum 8 x 8, current 1920 x 1080, maximum 32767 x 32767
eDP-1 connected primary 1920x1080+0+0
(normal left inverted right x axis y axis) 280mm x 160mm
1920x1080x60.00 60.05*+
1920x1080 60.05 + 59.93
1680x1050 59.88
1400x1050 59.98
1600x900 60.00 59.95 59.82
1280x1024 60.02
1400x900 59.96 59.88
1280x960 60.00
1368x768 60.00 59.88 59.85
1280x800 59.81 59.91
1280x720 59.86 60.00 59.74
1024x768 60.00
1024x576 60.00 59.97 59.90 59.82
960x540 60.00 59.63 59.82
800x600 60.32 56.25
864x486 60.00 59.92 59.57
640x480 59.94
720x405 59.51 60.00 58.99
640x360 59.84 59.32 60.00
VIRTUAL1 disconnected (normal left inverted right x axis y axis)
Configuration with the modesetting Driver - Method 2 of 2
Use the same setup as with the configuration for the Intel video driver for X.Org, except for Device sections (in my setup, in card.conf file) and Monitor and Screen sections (in my setup, in monitors.conf file).
Modify card.conf xorg configuration file.
% sudo vi /usr/local/etc/X11/xorg.conf.d/card.conf
% cat /usr/local/etc/X11/xorg.conf.d/card.conf
Section "Device"
Identifier "Card0"
Driver "modesetting"
Option "DPMS"
Screen 0
#BusID "PCI:0:2:0"
EndSection
Section "Device"
Identifier "Card1"
Driver "modesetting"
Option "DPMS"
Screen 1
#BusID "PCI:0:2:0"
EndSection
Modify the monitors.conf xorg configuration file.
% sudo vi /usr/local/etc/X11/xorg.conf.d/monitors.conf
% cat /usr/local/etc/X11/xorg.conf.d/monitors.conf
Section "Monitor"
Identifier "eDP-1"
Modeline "1920x1080x60.00" 141.00 1920 1936 1952 2104 1080 1083 1097 1116 -hsync -vsync
Option "DPMS" "true" # DPMS (Display Power Management Signaling)
EndSection
Section "Monitor"
Identifier "HDMI-2"
Modeline "2560x1080x75.00" 228.25 2560 2608 2640 2720 1080 1083 1093 1119 +hsync -vsync
Option "DPMS" "true" # DPMS (Display Power Management Signaling)
EndSection
# A Screen section ties a device (video card) to a monitor at a specific
# colour depth and set of display resolutions.
Section "Screen"
Identifier "Screen0"
Monitor "HDMI-2"
DefaultDepth 24
Device "Card0"
Option "ZaphodHeads" "HDMI-2"
SubSection "Display"
Depth 24
EndSubSection
EndSection
Section "Screen"
Identifier "Screen1"
Monitor "eDP-1"
DefaultDepth 24
Device "Card1"
Option "ZaphodHeads" "eDP-1"
SubSection "Display"
Depth 24
EndSubSection
EndSection
Restart Xorg (a.k.a. X, or X11, or X.Org).
% pkill Xorg
Footnotes
[¹] The default window manager supplied with X11 since the X11R4 release in 1989.
[²] Xephyr
(https://www.freedesktop.org/wiki/Software/Xephyr/)
Xephyr is a kdrive based X Server which targets a window on a host X Server as its framebuffer. Unlike Xnest it supports modern X extensions ( even if host server doesn’t ) such as Composite, Damage, randr etc (no GLX support now). It uses SHM Images and shadow framebuffer updates to provide good performance. It also has a visual debugging mode for observing screen updates.
Possible uses include:
Xnest replacement - Window manager, Composite ‘gadget’, etc. development tool.
Toolkit debugging - rendundant toolkit paints can be observered easily via the debugging mode.
X Server internals development - develop without the need for an extra machine / display.
Multiterminal with Xephyr - configuration is a single computer which supports multiple users at the same time.More information
See the README
https://cgit.freedesktop.org/xorg/xserver/tree/hw/kdrive/ephyr/README
[³] X Server Extensions
The X11 can be enhanced by adding extensions to the X server.
Examples of some of the extensions:
DPMS: Displays Power Management Signalling. Enables the X server to reduce monitor power consumption when not in use.
RANDR: Rotate and Resize. Notifies clients when the display is resized to a new resolution or rotated (especially useful on laptops, tablets and LCDs on pivot mounts) and enables the hot-plugging of monitors.
[⁴] Traditionally, the most important file for Xorg has been the xorg.conf configuration file.
Modern versions of Xorg do not create an xorg.conf file by default. In other words, using the X -configure is not recommended. Instead, on FreeBSD, various files ending in *.conf reside in the /usr/local/etc/X11/xorg.conf.d directory and are automatically loaded by X at boot, prior to reading any xorg.conf.
Configuration files will also be searched for in a directory reserved for system use. This is to separate configuration files from the vendor or 3rd party packages from those of local administration. In FreeBSD, these files are found in the directory /usr/local/share/X11/xorg.conf.d.
On my system used for this document:
% ls -lh /usr/local/share/X11/xorg.conf.d
total 14
-rw-r--r-- 1 root wheel 1.3K Jul 4 00:26 10-quirks.conf
-rw-r--r-- 1 root wheel 152B Jul 4 00:26 20-evdev-kbd.conf
-rw-r--r-- 1 root wheel 1.4K Jul 4 00:59 40-libinput.conf
You should not change what is included for system use in /usr/local/share/X11/xorg.conf.d directory.
It’s recommended to include your customizations or to override system settings by creating *.conf files in /usr/local/etc/X11/xorg.conf.d directory.
Note:
Names of these files are arbitrary and each file can contain one or more sections in the same format used by xorg.conf. Extension of the files has to be ‘.conf’.
Immediately after installing FreeBSD, I usually include the following two X configuration customizations:
Create a Module X configuration file to make sure that the freetype module is loaded. This file has a line Load "freetype" inside the "Modules" section:
$ cat /usr/local/etc/X11/xorg.conf.d/modules.conf
Section "Module"
Load "freetype"
EndSection
Create a keyboard layout customization file:
% cat /usr/local/etc/X11/xorg.conf.d/keyboard.conf
Section "InputClass"
Identifier "All Keyboards"
MatchIsKeyboard "yes"
Option "XkbLayout" "us, rs(latinunicode), rs"
Option "XkbOptions" "ctrl:nocaps,grp:rctrl_toggle"
EndSection
With this configuration file (/usr/local/etc/X11/xorg.conf.d/keyboard.conf), pressing the right Ctrl keyboard key cycles betweeen Serbian (latin), Serbian (cyrillic) and English (US) keyboard layouts, and ctrl:nocaps to ignore the Caps Lock key.
Note:
Alternatively, you can set your keymap in your $HOME/.xinitrc. For example, you can add a line setxkbmap rs -model pc105 to your .xinitrc file.
Note:
You can still create the xorg.conf file and continue making custom configurations in /etc/X11/xorg.conf as has been traditionally done but the file is not created by default.
From
5.4. Xorg Configuration - 5.4.1. Quick Start – FreeBSD Handbook
(Retrieved on Dec 20, 2021)
5.4.4.1. Directory
Xorg looks in several directories for configuration files.
/usr/local/etc/X11/is the recommended directory for these files on FreeBSD. Using this directory helps keep application files separate from operating system files.Storing configuration files in the legacy /etc/X11/ still works. However, this mixes application files with the base FreeBSD files and is not recommended.
5.4.4.2. Single or Multiple Files
It is easier to use multiple files that each configure a specific setting than the traditional single xorg.conf. These files are stored in the xorg.conf.d/ subdirectory of the main configuration file directory. The full path is typically
/usr/local/etc/X11/xorg.conf.d/.The traditional single xorg.conf still works, but is neither as clear nor as flexible as multiple files in the xorg.conf.d/ subdirectory.
References:
Introduction to Multiple Monitors in X - freedesktop.org
. . .
Dual-head Graphics Cards
Then came dual-head graphics cards with two physical monitor connections and things got complicated. It did not fit the one SCREEN, one card, one monitor scheme, so drivers had to invent ways to circumvent the X server architecture limitations.
One solution for a driver (DDX) is to create one SCREEN per head, which is called Zaphod mode (after Zaphod Beeblebrox, from the Hitchhiker’s Guide to the Galaxy). This has the drawbacks of multiple SCREENs, but you get the DPI right.
Another solution is to pretend that there is only one monitor, and use just one SCREEN, which is what the Nvidia TwinView mode does. TwinView avoids the drawbacks of the Xinerama feature, but has a completely non-standard way of configuring it. Plus, it is proprietary.
The third and the only proper way to deal with it is the RandR extension, which is a relatively new invention. RandR exposes the dual-head card as a single SCREEN, yet having a standard way of managing the multiple monitors. It avoids the Xinerama feature drawbacks, but uses the Xinerama extension to provide applications information about the physical monitor layout. RandR configuration can be controlled on the fly with the command xrandr, and it can be written to the X configuration file. The default configuration is cloned views, i.e. all heads show the same image.
With RandR:
This mode gives you two viewports over a single surface and the ability to size and position independently. Benefit is configurability, disadvantage is application support. If you are using a RANDR 1.3 capable distribution, you can also set “–primary” to provide a hint to gnome-panel et al. about which monitor is your “center of the universe”.
Disadvantage here is that applications are mostly naive when it comes to multi-monitor modes. They may listen to the xinerama extension and place things intelligently, they may not. This goes right up and down the stack.
X.Org/Dual Monitors - Single graphics card, Multiple X screens with ZaphodHeads:
. . .
Single graphics card, Multiple X screens with ZaphodHeads
In the previous example, a single PCI device was used to stretch a screen onto two separate displays. This will demonstrate how to use a single PCI device to provide two separate screens on two separate displays. This will, for instance, allow you to launch one program on a given display with DISPLAY=:0.0, and on another with DISPLAY=:0.1.
Motivation
It is often desirable to have multiple X screens produced by a single VGA controller. Most xf86-video-* drivers support Zaphod mode, which allows for a single device to produce multiple X screens. With intel graphics integrated onto all Sandy Bridge and higher CPUs, this is especially important.
For instance, on a machine with an on-chip graphics controller, as well as a separated video card, this would allow for one display for each output.
This example will focus on intel, though it should work with radeon and nouveau drivers that support it. . . .
Mailing List Archive: questions and sundry gripes about X11 multihead (it’s a rant):
(Posted on Dec 29, 2013)
After years of assuming I’d probably never set my system up with multiple monitors, I’ve decided to go ahead and do it. I’ve watched with some interest as various new schemes for doing it have emerged over the years (Xinerama , and now lately RandR), but I’ve always assumed that if nothing else, good old Zaphod mode would always be around, since it’s built right into the way X11 numbers $DISPLAY (0:0, 0:1, 0:2…etc.). It’s been around so long, it’s older than Linux itself.
. . .Anyway, Zaphod is what I want. I don’t care that it won’t let me drag windows between monitors. That’s precisely the advantage of it. Many applications are written with such an assumption of a single display that it’s best not to disappoint them. I don’t want to worry about what a full screen game will think of my multihead setup. I don’t want to see dialog windows (or anything else really) popping up, half on one monitor and half on another. I don’t want to have to setup the arrangement of my desktop so that it’s arranged to not look ridiculous at the point where the two monitors divide the screen. It’s all just simpler if we have two screens that are completely separate, and the only magic object that’s able to move between them is the mouse pointer.
I’m not complaining that we have RandR now. I think it’s great. One of X11’s greatest weaknesses has always been that before now, you couldn’t really make any big configuration changes while the X server is running. Now, thanks to RandR, you can do almost anything with your desktop running and active, and you don’t even need root access. You can’t configure Zaphod type multihead that way, but that’s fine – you couldn’t do that before either (nothing gained, nothing lost). But RandR lets you make almost any other desktop geometry change as a regular user without restarting X, and I think that’s great.
RandR (and its predecessor, Xinerama) both assume though that if you’re doing multihead, you want one big screen that spans multiple monitors. Nice if that’s what you want, but as detailed above, there are good reasons why you might prefer otherwise.
Posted on Dec 29, 2013
Permalink:
https://lists.archive.carbon60.com/gentoo/desktop/282080#282080
How to Set Up Dual Head for Intel Graphics with RandR 1.2 - 01.org Intel Open Source
How to configure X for multi-head with two separate screens?
Separate screens - Multihead - ArchWiki
X.Org legacy driver for Intel integrated graphics chipsets – x11-drivers/xf86-video-intel
Multiseat gaming with multi-pointer X
Switch monitors in xorg.conf in a dual screen setup
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