SUMMARY When running kwin_wayland nested, it does not support a command line argument --scale of < 1 STEPS TO REPRODUCE 1. Follow the instructions here: https://community.kde.org/KWin/Wayland#Starting_a_nested_KWin for a nested wayland instance 2. Set the command line switch --scale to a value less than 1 e.g. 0.5 OBSERVED RESULT FATAL ERROR incorrect value for scale EXPECTED RESULT Should allow a scale of < 1. E.g. 0.5 (50%) When using an existing session and using the display configuration it's possible to set a scale of 0.5 so this seems to be a redundant check at startup: The error message comes from main_wayland.cpp:612 https://github.com/KDE/kwin/blob/master/main_wayland.cpp#L612 Use case: I have an older game that doesn't support MSAA and was trying to render it at a higher resolution and scale it down, a bit like how DSR works in the windows nvidia driver.
Git commit b46d148476948f30f70d0a2b58d0772d57c25942 by David Edmundson. Committed on 27/05/2020 at 17:51. Pushed by davidedmundson into branch 'allow_smaller_scales'. [wayland] Allow nested mode to have a fractional scale < 1 The bug reporter presents a use case of wanting to run a game and scale down the result. For everyone else kwin_wayland nested is just a test tool, so I don't see any disadvantages. It could be useful in testing. M +1 -1 main_wayland.cpp https://invent.kde.org/plasma/kwin/commit/b46d148476948f30f70d0a2b58d0772d57c25942
Ignore gitlab getting a bit excited there. Patch on review https://invent.kde.org/plasma/kwin/-/merge_requests/28
The relevant fix has been merged. Not sure why the bug report wasn't closed.