No Optimus in Debian
Because it took me a while to figure out, I’m writing this down: Debian does not support Optimus out of the box. Nor does it seem to come with a package that can configure it for you. Unless you use the Nouveau drivers, in which case I think the NVidia GPU is always on.
I’ve a couple of old laptops, which I am using as server and HTPC. Lately I’ve discovered the Dolphin emulator, which runs fine on these old GPUs with Nouveau. But, with Nouveau I see horrible screen tearing when watching video, so, I thought I’d install the NVidia drivers, because that used to work well (10 years ago). The chips are so old they require NVidia’s 390 driver, which Debian 12 doesn’t ship anymore, but even with Debian 11 I couldn’t get X to start when I forced the NVidia driver (which I had to do manually, because if not it’d just use the Intel GPU). So, on a hunch I decided to try Ubuntu 22.04 (also the last LTS to ship with 390 by the way, so I guess these machines’ days are numbered). Lo and behold, even without making a xorg.conf was Optimus properly configured (the DE reports the Intel GPU, but any OpenGL application the NVidia GPU). The NVidia panel no longer complains I’m not using an NVidia chip, so, all good!
What does this mean? That I hate Debian now! At least, for these Optimus laptops (I have 3…). I suppose a sudo apt purge snap is worth my machines working properly. I’m too time-constrained to try other distros, which I probably don’t want anyway: these machines are pretty appliancy, so only maybe CentOS would be an option but of course CentOS never is so no.
Pity, dear friend Debian, I really hate to divorce you!