Dynamic overlay injection

[fililip]

What would be required to enable dynamic injection to an already running process (ie to avoid having to restart a videogame)?
Are there kernel-mode/user-mode driver limitations, or is it impossible on the Linux kernel?

[17314642]

Why not just hide it at the start?

[17314642]

To inject into the running process, you need either root rights or configuring the kernel to ptrace other binaries without root. Thats how csgo cheat for linux did it.

They injected using gdb debugger with root.

You can actually try and inject opengl version of mangohud with gdb, maybe it already works.

Not really sure about vulkan though. Maybe it also works

[fililip]

Why not just hide it at the start?

It's more about being able to choose what gets the overlay in the first place - I have a frame limiter by default, and I don't want it for every app (due to 160 FPS - 165Hz mismatch and thus stuttering), but sometimes I forget to set mangohud %command% on an already launched game, and in the case of some long-to-load games it is a bit of a chore to have to restart the game for the frame limiter.

[17314642]

Also, even though this is probably possible to do, this approach will not work in a flatpak environment.

[fililip]

I've reevaluated this, and concluded that this is probably too much work for little gain (both for the devs and users), sorry for the noise 🙏