Forum Discussion
New ContributorQuesta-ModelSim UI scaling problems in Linux
Hello
Has anybody been able to solve the issue of UI of Questa not scaling correctly on linux with wayland?
I am using Ubuntu 26.04 with wayland and UI is just tiny, icons, are so small i cannot read any text.
When opening a new project, file explorer is also tiny.
Fonts i could change in the config file but icons, menus and everything else is just extremely small.
Problem is even worse on high resolution displays.
Regards, Haris
14 Replies
ZiYingE_AlteraContributor
Hi haris,
This appears to be GUI scaling under Wayland, particularly with Qt-based applications on high-DPI displays.
Regarding the font changes, were those made through the ~/.modelsim settings file? May I also check which Questa version you are using?
As a workaround, could you try launching Questa with the following commands:
export QT_SCALE_FACTOR=2
export QT_AUTO_SCREEN_SCALE_FACTOR=0
vsim
QT_SCALE_FACTOR=2 tells Qt to scale the application UI to 200%, which can help enlarge icons, menus, dialogs, and other GUI elements.
QT_AUTO_SCREEN_SCALE_FACTOR=0 disables Qt's automatic scaling detection and forces it to use the scale factor specified above.
You may need to adjust QT_SCALE_FACTOR (for example, 1.5, 2, or 2.5) depending on your display resolution and desktop scaling settings.
Could you please give this workaround a try and let me know whether it improves the GUI scaling on your system.
Regards,
ZiYingE_Altera- ZiYingE_Altera
Hi haris,
Just wanted to follow up on my previous message in case it was overlooked.Have you had a chance to try the suggested steps? Feel free to let me know if you encounter any issues and need any assistance.
Thank you.
Regards,
ZiYingE_Altera- ZiYingE_Altera
Hi haris,
Just wanted to follow up on my previous message in case it was overlooked.If there are no further questions or concerns, may we proceed with closing this ticket for now?
Thank you.
Regards,
ZiYingE_Altera
fmasmitsI have tried the above methods, but this did not seem to work for me. I am also using Ubuntu 26.04. I attempted various values for the QT_SCALE_FACTOR, but nothing seems to change. Are there possibly any other solutions to this problem?
- ZiYingE_Altera
Hi fmasmits,
May I know which Questa version and edition you are currently using?
Could you also provide a screenshot demonstrating the UI scaling issue?
In addition, could we try the following steps? This will help us determine whether the issue is related specifically to Wayland or if it also occurs when using X11.
1. Open a terminal.2. Check whether ModelSim is available by running:
which vsim
3. If a path is printed, launch ModelSim with the X11-compatible backend:QT_QPA_PLATFORM=xcb vsim
However, this only applies to Questa launched with the command above and will not affect Questa instances launched without it.
Once you have tried the above steps, feel free to let us know the results.
Thank you.
Regards,
ZiYingE_Altera
- fmasmits
Hello ZiYingE_Altera,
See the below screenshot for the scaling issue. Note that the text is 'decently' scaled because I already manually changed a lot of numbers in the ~/.modelsim file. The version that I am using is "FPGA edition 2025.2".Here is the feedback on the steps you recommended me to try:
1. Running which vsim:
fsmits@fsmits ~/D/f/p/s/m/a/s/testbench (feature/control_module)> which vsim
/altera/25.1std/questa_fe/bin/vsim
2. launching ModelSim with the X11-compatible backend:
fsmits@fsmits ~/D/f/p/s/m/a/s/testbench (feature/control_module)> QT_QPA_PLATFORM=xcb vsim
Reading pref.tcl
To which modelsim boots up looking the same as it did without the QT_QPA_PLATFORM=xcb prefix:Thank you very much for the swift response! Hopefully we can figure out a solution.
cheers,
Finn- ZiYingE_Altera
Hi fmasmits,
Thank you for the update and for trying the suggested steps.
May I know the resolution of your monitor?
Thank you.
Regards,
ZiYingE_Altera- ZiYingE_Altera
Hi fmasmits,
Just to add to my previous question, besides the monitor resolution, could you also share the desktop environment you are using?
You may run with the following command in the ubuntu terminal:
echo $XDG_CURRENT_DESKTOP
echo $XDG_SESSION_TYPE.
This will help us better understand the display environment on your system.
Thank you.
Regards,
ZiYingE_Altera
- fmasmits
Dear ZiYingE,
I have three monitors that I can use. They have the following resolution:
3840 x 2160 (16:9)
1920x1200 (16:10)
3440 x 1440 (21:9)
The desktop environment is GNOME with wayland. But here are the commands anyways:
fsmits@fsmits ~/Downloads> echo $XDG_CURRENT_DESKTOP
ubuntu:GNOME
fsmits@fsmits ~/Downloads> echo $XDG_SESSION_TYPE
wayland
cheers,
Finn- ZiYingE_Altera
Hi fmasmits,
Thank you for the prompt response.
Just to confirm, regarding the Questa scaling issue, does it occur on all three monitors, or only on a specific monitor?
Thanks.
Best regards,
ZiYingE_Altera
- fmasmits
Hello ZiYingE_Altera,
It appears on all screens.
Even if I reduce the resolution through OS settings, it changes nothing.
cheers,
Finn- ZiYingE_Altera
Hi fmasmits,
Thank you for the update.
I am currently looking into resources to reproduce the issue on my end and will keep you updated on any findings.
In the meantime, please feel free to let me know if you notice any additional observations that may help with the investigation.
Regards,
ZiYingE_Altera - ZiYingE_Altera
Hi fmasmits,
Just to provide some additional clarification, Ubuntu 26.04 is not yet officially supported by Questa Altera FPGA Edition.
As a result, unexpected behavior or issues may occur since this operating system has not yet been fully validated. You may refer to the supported operating systems here: https://www.altera.com/design/guidance/software/os-support
In the meantime, I will see if I can obtain access to another supported Ubuntu version on my end to help reproduce and investigate the issue further.
Thank you.
Regards,
ZiYingE_Altera
harisI would like to provide few updates as well, because I have the same issue as fmasmits.
The problem started with questa, when i switched to 4k Monitor. This is almost certainly a wayland issue. I had to enable Ubuntu fractional scaling, because otherwise everything would look too small.
I enabled 150% scaling for desktop settings.
Please notice there is also an option now in ubuntu that says "Automatically scale legacy applications". If this is enabled Questa becomes too small, it does not scale as expected.
Try turning this option off. then for some reason certain x11 apps look better, at least size is normal, but then cursors etc. are scaled out of proportion.
