[Nix-dev] Experiences with Nvidia Optimus?

[Mathijs Kwik]

On Sat, Jan 14, 2012 at 11:01 AM, Arie Middelkoop <amiddelk at gmail.com> wrote:
> Hi,
>
Hi Arie,

> Does any of you have experience with getting hardware acceleration for
> nvidia optimus laptop videocards (e.g. GT555M) to work? My fresh new laptop
> with Nixos is getting into a workable state, but this videocard issue seems
> quite a pain.

I have a similar laptop and checked some 6 months ago (bumblebee then).
Although it worked, I did not bother much. For gaming, I dual boot
windows, which turned out to be a lot easier than using wine (which
works great for some games, but takes time to investigate per game how
to setup, and newer DX11 stuff doesn't work and copy protection gets
in the way).

My intel card gives a decent performance for what I do (composited
desktop, 1080p video, light 3d stuff like blender) under linux, so no
need for nvidia there.

>
> If I understand the webpages that I read so far correctly, the difficulty
> with this optimus technology seems to be that the nvidia card is acting like
> a coprocessor for the intel videocard inside the processor. The nvidia card
> is thus not physically connected to any screen. When I start X with only the
> nvidia driver enabled, it does recognize the device, but does not find any
> screen. When I load the driver for intel as well, then it only uses the
> intel card.
>
> There seems to be an Ubuntu package called Ironhide (called before:
> Bumblebee, and before that Optimus Prime) that somehow seems to address this
> issue, so that you can actually map applications to a particular device (or
> something like that). I was wondering if any of you had experience with
> this?

I got it working under arch linux (which had user-made packages in
their AUR repo).
It allows you to start an application on the nvidia card and have it
output overlayed over your intel stuff.

There is no way to move running apps between cards, so it's really a
per-launch choice (which is fine most of the time).
For non-fullscreen applications, I had minor issues/glitches around
the windows that were drawn by nvidia.
Especially trying to cover the window sometimes gave lockups.

>
> I'm trying to read up on things, but documentation is rather scarce. What is
> particularly confusing me is that in some descriptions the name
> "nvidia-current" is used to refer to a nvidia driver, which is apparently
> different from "nvidia"...

nvidia-current is the name ubuntu gave to their current nvidia
offering, instead of making nvidia a metapackage to depend on some
versioned one.
Other than that, it's the normal driver. I think this might be related
to "nvidia" switching to nouveau in the future (or they already did).

With Arch I needed the bumblebee package, as the normal nvidia driver
wants to install its GL libs as system default (meant for nvidia-only
setups).
I think with nix, they might be able to coexist, as long as no nvidia
stuff gets loaded for X11 itself (which wants to perform a full
takeover).
I don't remember the details though, sorry.


>
> Although it is likely a separate issue, when using the intel driver, all KDE
> popdown menus have a graphical corruption (e.g. fully black), whereas e.g.
> popup menus in Chrome do not have any corruption. But this is an incentive
> to me to put in some effort to get it up and running properly :)

Yes, that issue is fixed in intel 2.15, patch here
https://github.com/bluescreen303/nixpkgs/commit/a0f72db5786f9272735c5a797c4a1fb878de2587
I know 2.17 is available in nix repo, but it didn't compile (missing
deps). Officially 2.15+ should need newer xorg-server/mesa libs, but I
don't have issues.

>
> Cheers,
> Arie
>
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