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I use it. It works. I lucked into a semi-obsolete high-end gamer machine with a 6-core i7 and 24GB of memory and three full-length PCI-Express slots. I leave

I use it. It works. I lucked into a semi-obsolete high-end gamer machine with a 6-core i7 and 24GB of memory and three full-length PCI-Express slots. I leave my machine on. The standby power of this monster (850W power supply) was too high to justify. So I tried it. Three video cards in the three slots. Came right up, the Linux desktop extended seamlessly across any monitor plugged into any of the cards (a mix of AMD and Nvidia no less). Enter multi-seat. A few "sticky" commands later (i.e. only needed for reconfiguration, not on every boot) I have three user stations, each with monitor, keyboard, mouse, audio and at least one dedicated USB socket. Works a treat. It's not 100% bulletproof; crashes to the point of needing a reboot maybe 2-3 times a year, but aside from that indistinguishable from dedicated computers for each screen. Stock Fedora 28. Here's the sum total of commands needed to set up the multiseat in my setup (seat 0 gets everything not assigned to the others). loginctl attach seat1 /sys/devices/pci0000:00/0000:00:09.0/0000:05:00.0/drm/card0 /sys/devices/pci0000:00/0000:00:09.0/0000:05:00.0/graphics/fb0 /sys/devices/pci0000:00/0000:00:1a.7/usb1/1-5 loginctl attach seat2 /sys/devices/pci0000:00/0000:00:07.0/0000:04:00.0/drm/card2 /sys/devices/pci0000:00/0000:00:07.0/0000:04:00.0/graphics/fb2 /sys/devices/pci0000:00/0000:00:1a.7/usb1/1-3 loginctl attach seat2 /sys/devices/pci0000:00/0000:00:1a.7/usb1/1-4/1-4.1/1-4.1.4/1-4.1.4:1.2/0003:046D:C52B.00A3/0003:046D:4004.00A4/input/input194 loginctl attach seat2 /sys/devices/pci0000:00/0000:00:1a.7/usb1/1-4/1-4.4/1-4.4:1.0/0003:045E:00B9.00A5/input/input195 I hope this functionality doesn't turn into abandonware before I'm done with this monster machine i.e. it breaks or becomes too obsolete. I did in the past try to set up multiseat, just for fun, with a Displaylink box, after reading the article about it, but got nowhere, with the distinct feeling that they got it working once, and then abandoned it.

MarkusWandel 7y ago
A few more details. One thing that doesn't work very well is storage devices. For one thing, as soon as one appears, the (non-multiseat aware) file managers all jump on it and try to mount it. And two of the three get a password prompt because they don't own the USB socket, and tie up the device so the one that does can't mount it. Solution: Turn off automount, and only use storage devices from seat 0. You run into occasional other "more than one user per computer" issues. For example, trying to access the same UDP RTSP camera from VLC on two different desktops. And the three desktops do get actively used by three differerent family members. Linux on the desktop for non-geeks/kids? Nobody cares. As long as the browser works with full video capability (smooth 1080p Youtube) and, in the child's case, the Tuxpaint painting program, everybody happy.
- MarkusWandel 7y ago
  I keep thinking of more stuff to add. Multiple monitors: Well, a typical video card has two output sockets and easily drives two monitors. So why not two users? Because multiseat only works if each session gets to own its video chip, in its own private instance of Xorg or Wayland. There are hacks to split it by overlaying nested servers onto the one that owns the chip, but they have awful video performance (I tried it). So you do need the multiple video cards (and slots to put them into). One per user. And even more idle power consumption. But the 124W that the machine now sucks down 24/7 is sort of justifiable in that it serves the whole family's browsing/computing needs aside from a few smartphone type gadgets. And the setup is physically robust, in a household with small children, in a way that laptops just aren't. Cheap 7m HDMI cables and active USB extension cables (from Ali Express) take care of the physical separation between stations. Sound is easy as long as you get it over HDMI - no need to configure a separate device, it comes with the video. But one of the stations owns the physical audio sockets on the motherboard, and one, for reasons too complicated to get into here, uses network audio over another Lennart special -Pulseaudio. That has its own frustrations, but the remote audio, once I got it working, has been solid.
  - geofft 7y ago
    Thanks for the detailed reply! Also, are you using wired networking for remote audio? Last time I tried PulseAudio remote audio over wifi it instantly made wifi useless for everyone in the house. (Honestly I wouldn't mind mildly lossy compression, but there doesn't seem to be support for that.)
    - MarkusWandel 7y ago
      Wired, of course. Though I did accidentally configure the sending instance of PA to send multicast pakcets. Which it did, with abandon, even when no audio was playing, saturating the wifi to such an extent that I was driven to despair before I figured it out. Consumer grade Wifi gear, even if loaded with, say, OpenWRT, does not handle overload gracefully. PA configuration is a confusing mix of config files and GUI stuff.

MarkusWandel 7y ago

A few more details. One thing that doesn't work very well is storage devices. For one thing, as soon as one appears, the (non-multiseat aware) file managers all jump on it and try to mount it. And two of the three get a password prompt because they don't own the USB socket, and tie up the device so the one that does can't mount it. Solution: Turn off automount, and only use storage devices from seat 0. You run into occasional other "more than one user per computer" issues. For example, trying to access the same UDP RTSP camera from VLC on two different desktops. And the three desktops do get actively used by three differerent family members. Linux on the desktop for non-geeks/kids? Nobody cares. As long as the browser works with full video capability (smooth 1080p Youtube) and, in the child's case, the Tuxpaint painting program, everybody happy.

MarkusWandel 7y ago
I keep thinking of more stuff to add. Multiple monitors: Well, a typical video card has two output sockets and easily drives two monitors. So why not two users? Because multiseat only works if each session gets to own its video chip, in its own private instance of Xorg or Wayland. There are hacks to split it by overlaying nested servers onto the one that owns the chip, but they have awful video performance (I tried it). So you do need the multiple video cards (and slots to put them into). One per user. And even more idle power consumption. But the 124W that the machine now sucks down 24/7 is sort of justifiable in that it serves the whole family's browsing/computing needs aside from a few smartphone type gadgets. And the setup is physically robust, in a household with small children, in a way that laptops just aren't. Cheap 7m HDMI cables and active USB extension cables (from Ali Express) take care of the physical separation between stations. Sound is easy as long as you get it over HDMI - no need to configure a separate device, it comes with the video. But one of the stations owns the physical audio sockets on the motherboard, and one, for reasons too complicated to get into here, uses network audio over another Lennart special -Pulseaudio. That has its own frustrations, but the remote audio, once I got it working, has been solid.
- geofft 7y ago
  Thanks for the detailed reply! Also, are you using wired networking for remote audio? Last time I tried PulseAudio remote audio over wifi it instantly made wifi useless for everyone in the house. (Honestly I wouldn't mind mildly lossy compression, but there doesn't seem to be support for that.)
  - MarkusWandel 7y ago
    Wired, of course. Though I did accidentally configure the sending instance of PA to send multicast pakcets. Which it did, with abandon, even when no audio was playing, saturating the wifi to such an extent that I was driven to despair before I figured it out. Consumer grade Wifi gear, even if loaded with, say, OpenWRT, does not handle overload gracefully. PA configuration is a confusing mix of config files and GUI stuff.