Access to SharedMemory

I’m debugging in issue of our application that occurs only with the recently released flatpak. Our application can run in Single Instance mode and we check if another instance is already running by creating an entry in shared memory https://doc.qt.io/qt-5/qsharedmemory.html. Works on all kind of Distros, Windows, in Snap too but with the flatpak we seem to have a problem. Should we be able to use SharedMemory in Flatpaks? Do we need to enable something in the manifest?

You need --device=shm for that, see https://github.com/flatpak/flatpak/blob/ec59cd6b5e536c2997c9ea88ee9763506c21c401/NEWS#L121. You will also need to enforce the required flatpak version with --require-version=1.6.1 on finish-args.

Thanks, we were able to resolve this by fixing another issue, it looks like it had something to do with permission to the/tmp directory.