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Thread: Linux, WSJT-X and multi monitors

  1. #1
    Administrator N8YX's Avatar
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    Linux, WSJT-X and multi monitors

    An amalgamation of sorts. Figured I'd post this in the Computers section in case someone else runs into the same problems I did:

    The old shack computer (Windows 7) keeps on chugging away for things like controlling my various scanners via deprecated software packages. One of our new members (Mark, KE8NOA - an area 10M friend) convinced me to dip my toes in the FT8 waters, but the software requires an active Internet connection for time-sync purposes. No way I'm letting a Win7 box out on the 'Net (unless it's a VM that I can easily re-image) so I had to look at alternatives.

    On this system (Shuttle SH67H3) Window 10 running as a host OS is questionable. That is, I've had more stability problems than running Mint Tricia (19.3) as a host, with Win10 as a guest. To be fair, Windows support of multi-monitor configurations (especially those connected via USB) is a bit better than various Linux iterations. I was weighing my options when Mark and I were chatting about WSJT-X on 10M and he remarked that he was successfully running the Linux version on Tricia 19.3. This galvanized me to give it a shot. Which went well - I removed the SignaLink connection from my Win7 system and it was pretty much a seamless integration with the Linux host. K1JT's site provides a how-to for the Linux installation.

    Except for one little problem: My work area has four monitors - a 17" flat panel, two 24" flat panels and a second 17" flat panel. I can utilize the two 24" and rightmost 17" on my work PC while doing my day job, or switch video inputs via KVM or the monitors themselves and route them to one of several shack computers - including the Tricia host. What I missed with that setup is the ability to use the left 17" monitor as an fldigi (PSK31) or WSJT-X screen. That way I can work, monitor the on-air goings-on and click to QSO if I see something neat pop up on the digi-modes monitor. A number of USB-to-video adapters are on-hand here, most of which have DisplayLink hardware embedded in them. None would work quite right with this version of the OS so a little digging turned up a Diamond BVU-195. When I installed it, Tricia's native driver support picked up the device but it wouldn't let me initialize the monitor at its highest resolution. DisplayLink has Ubuntu drivers on their site - I downloaded the pre-20.x version, installed a few dependent packages then installed the driver and rebooted. All looks good except for the mouse pointer disappearing when the DisplayLink adapter was active.

    We'll cut to the chase with a synopsis of what I did to make things work, after much Internet searching:

    1) The EVDI driver has to have an entry in /etc/modules. Do this by "echo evdi >> /etc/modules". Similarly, in the /etc/modprobe.d directory an evdi.conf file must exist. Create it by entering 'echo "options evdi initial_device_count=1" >> /etc/modprobe.d/evdi.conf' (Use a value greater than 1 if you have more than one DisplayLink device attached to the computer).

    2) My system required an entry in /etc/X11/Xsession.d to set display parameters using xrandr. The arguments used will vary from system to system, but in a nutshell I have three video devices connected - two onboard (DVI and HDMI). The DVI port is connected to an analog VGA cable through an adapter and the system thinks it's talking to a VGA device. It also never sets the VGA video mode correctly on startup. Thus, my xrandr file (named 90xrandr) issues a resolution set command then sets the primary video device (the VGA screen), sets display positions and finally turns the DisplayLink device on.

    3) The mouse needs to be set to its fastest acceleration using the appropriate Settings applet. I used a "Custom Speed" with the slider all the way to the right.

    4) Lastly, this DisplayLink article provided a solution to cure the mouse misbehavior - https://support.displaylink.com/know...ent-x-upgrades

    I'm currently running the system on two of the three monitors - the rightmost 24" and the leftmost 17", which is the display being used for WSJT-X. Performance appears solid. The leftmost 24" can be toggled back and forth between work and play computers.
    "Everyone wants to be an AM Gangsta until it's time to start doing AM Gangsta shit."

  2. #2
    Mystical Drummer NM5TF's Avatar
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    I assume that you did something like this article suggests....https://www.instructables.com/How-to...tors-in-linux/

    tommy
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    Administrator N8YX's Avatar
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    Quote Originally Posted by NM5TF View Post
    I assume that you did something like this article suggests....https://www.instructables.com/How-to...tors-in-linux/

    tommy
    Tommy,

    Tricia is usually really good at auto-configuring multihead setups as long as the devices themselves are present (thus the modprobe entries). Some implementations of the Intel driver don't properly report all resolutions a given monitor can support (especially when the various displays are connected to different output technologies) and thus you have to force the issue...so to speak.

    Other video adapters give me nary a bit of trouble, but since all the slots in this system are tied up with comms peripherals you have to work with what you have and use the onboard device along with the driver.
    "Everyone wants to be an AM Gangsta until it's time to start doing AM Gangsta shit."

  4. #4
    Administrator N8YX's Avatar
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    Thread bump:

    It appears the latest version of Mint (21.3) automatically detected the two USB/DVI adapters when I installed it. The only thing I had to do was copy the "90xrandr" file into /Xsession.d to be able to set the primary display to its maximum resolution. More testing today (subject of another thread) but it's nice the drivers apparently made it into the system.
    "Everyone wants to be an AM Gangsta until it's time to start doing AM Gangsta shit."

  5. #5
    Administrator N8YX's Avatar
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    Update:

    I got the latest DisplayLink drivers (Ubuntu 22.04LTS) from their site, installed and started playing around with them. May not have needed to, as the system seemed to recognize the other monitors as installed.

    Positioning is still a little fiddly but if one is patient, all of the USB-connected monitors come up where they're configured. You aren't going to run 4K movies on these but for things like running a VM with ham radio programs installed they work fine.
    "Everyone wants to be an AM Gangsta until it's time to start doing AM Gangsta shit."

  6. #6
    Forum Addict n6hcm's Avatar
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    what is truly shocking is *how many decades this has taken* to be done approximately correctly. in 1986, when we first messed with the x window system, this was an issue. in 2024 this should have been solved at least 20 years ago.
    "... and another thing about you democrats ... you all believe in science!" -- denny crane

  7. #7
    Administrator N8YX's Avatar
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    Quote Originally Posted by n6hcm View Post
    what is truly shocking is *how many decades this has taken* to be done approximately correctly. in 1986, when we first messed with the x window system, this was an issue. in 2024 this should have been solved at least 20 years ago.
    If one goes to LinkedIn or the other professional networking sites, one will find my employment history (though I really ought to update the latest chapter...).

    In the early 2000s I was the first person to get Linux multi-head support working on a previous employer's PC hardware. The fact they were using 8xx-series chipsets as the primary video devices and el cheapo video cards as the secondary (consumer) display certainly didn't help. WinXP, NT4, Win2000 etc. simply didn't care, however - if the appropriate video drivers were loaded, multi-monitor was good to go right out of the box.

    As fair as I know they never did move to a Linux-only solution for their products. Datacenter use, however, was another animal entirely.
    "Everyone wants to be an AM Gangsta until it's time to start doing AM Gangsta shit."

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    Pope Carlo l NQ6U's Avatar
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    Yeah, it’s weird that it’s taken so long for Linux to catch up when it comes to multiple monitors. MacOS has been doing it without. a hitch since at least the early 90s.
    All the world’s a stage, but obviously the play is unrehearsed and everybody is ad-libbing his lines. Maybe that’s why it’s hard to tell if we’re living in a tragedy or a farce.

  9. #9
    Forum Addict n6hcm's Avatar
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    well, they've had them for. a while but it was never usefully easy. there was always a sacrificial. chicken, and some documentation you had to get from a guy who knew a guy. it's not like on contemporary desktops. where this is configurable in an expected place.
    "... and another thing about you democrats ... you all believe in science!" -- denny crane

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