Created attachment 119288 [details] An distorted example SUMMARY When connecting via VNC from one openSUSE Tumbleweed system to another, I harvest: screen distortions in medium quality, and a saturated GBit ethernet connection with high quality. Only low quality behaves, but suffers from quality perspective (as expected)- STEPS TO REPRODUCE 1. use krdc 19.03.80 and below using VNC from TW 20190403 to TW 20190403, 2. choose medium quality, no forced resolution, no scaling 3. connect OBSERVED RESULT screen displays okay for the first draw, then more and more distortions appear EXPECTED RESULT proper display SOFTWARE/OS VERSIONS openSUSE Tumbleweed 20190403 KDE Frameworks 5.56.0 Qt 5.12.2 (kompiliert gegen 5.12.2) Das xcb Fenstersystem ADDITIONAL INFORMATION krdc built here: https://build.opensuse.org/package/show/home:frispete:Tumbleweed/krdc The other end has VNC enabled within /etc/X11/xorg.conf.d/10-libvnc.conf: Section "Module" Load "vnc" EndSection Section "Screen" Identifier "Screen0" Option "SecurityTypes" "VncAuth" Option "PasswordFile" "/root/.vnc/passwd" EndSection Running kdrc with debug options results in: KRDC: Wallet OK KRDC: Password read OK KRDC: "VNC authentication succeeded" KRDC: "Desktop name \"\b\"" KRDC: "Connected to VNC server, using protocol version 593193168.593193392" KRDC: "VNC server default format:" KRDC: "593193136 bits per pixel." KRDC: "\b significant byte first in each pixel." KRDC: "TRUE colour: max red 593193120 green 593193344 blue 16, shift red 8 green 8 blue 593193344" KRDC: Client created KRDC: 3 "Verbunden." "tw.lisa.loc" : 5900 KRDC: TCP keepalive set KRDC: --------------------- Starting main VNC event loop --------------------- KRDC: 1 KRDC: 2 KRDC: 3 KRDC: Found URL. Move it at the history start. KRDC: Write wallet password KRDC: Updating framebuffer size KRDC: Resizing: 1920 1200 KRDC: tabwidget resize, view size: w: 1920 , h: 1200 KRDC: new window size: QSize(1920, 1270) available space: QSize(2560, 1560) The other end is using 1920x1200x24 and kdm due to sddm missing XDMCP... The krdc vnc lib is libvncclient1-0.9.12-1.1.x86_64, and tigervnc on the server is 1.9.0. I've tried a couple of older krdc revisions, but the problem persists.
Possible fix for this issue: https://phabricator.kde.org/D20123
Well, the patch applied cleanly to 19.03.80, but no cake, unfortunately. Could there be other similar accesses in different code paths? Anyway, I've checked in the fix in my repo for documentation purposes... I forgot to mention, that other VNC clients (vncviewer, bVNC Pro on Android) act just nice, but I don't know, which connection parameters they use exactly. I've checked LibVNCclient and tigervnc github states. The former shows no significant changes, but the latter does many. Will try to replace that package on the server as a next step (sometimes this week, hopefully).
Okay, tigervnc-1.9.0 was the culprit. After applying git master, all is well. For the record, the fixed package: https://build.opensuse.org/package/show/home:frispete:RemoteDesktop/tigervnc Sorry for the churn. Will report a few lesa impacting issues soon (that definitely origin from krdc ;-))