Xlib: missing extension "XFree86-VidModeExtension" after upgrade to 16.04

[trzecieu]

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• A brief description After installing an update to Windows 10 Creators Update I've started to have a problems with running one project due: Xlib: extension "XFree86-VidModeExtension" missing on display ":0.0".. This project was running nicely on previous WSL based on 14.04. Before installing an update I removed my Linux files by command lxrun /uninstall /full. Then after reinstall WSL I installed required packages for my project: libx11-dev libglu1-mesa-dev libxxf86vm-dev and recompiled my project. As a sanity check, I verified if gvim and firefox work with WSL, and they do.

In order to fix this problem I've tried as follow:

piotr@DZIK:/$ cat /etc/X11/xorg.conf
Section "Module"
        Load "extmod"
EndSection

But it didn't help.

My project uses: XF86VidModeQueryVersion, XF86VidModeGetAllModeLines

• Expected results Application what uses VidModeExtension should work like with 14.04

• Actual results (with terminal output if applicable)

• Your Windows build number 1703

• Steps / All commands required to reproduce the error from a brand new installation

• unfortunately I haven't seen any publicly available application what uses it.

• Strace of the failing command strace.txt

• Required packages and commands to install

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[aseering]

Hi @asRIA -- so, WSL by itself is text-mode only. While it's true that the functions that you listed above aren't implemented in stock WSL, that's because WSL itself doesn't implement any X functions :-)

My guess is that you installed a third-party X server such as VcXsrv or Xming a while ago, and configured WSL to use it to handle X Windows calls. That third-party server is what needs to support these features. Note that these third-party X servers are Windows applications; you'll have to find and edit their config files on the Windows side.

[trzecieu]

Thank you @aseering for a good answer for it. You were right :)

---

Update: Just for the others to clarify what's wrong: in 14.04 XF86VidModeGetAllModeLines doesn't work also. Error was placed in my code, where I didn't check if returned number of modes isn't 0. (Yeapp). And I copied the first mode into stack value. For 14.04 it copies some garbage, but in general no exception is thrown. In 16.04 I'm getting memory access validation, and my application crashes.

In both cases I'm having log Xlib: extension "XFree86-VidModeExtension" missing on display ":0.0". But because in 16.04 it was the first and last log what I saw, I thought that this is a reason of my problem.