xorg.conf-less configuration with Nvidia Optimus

mounty1 · l33t Joined: 06 Jul 2006 Posts: 955 Location: Queensland

Following-on from my earlier question about Nvidia optimus with two external displays, I've installed Mint 20 on the same laptop and it is running all three displays. Sometimes a bit flickery but not too bad. It is doing this without an xorg.conf which means that all the stuff about modesetting, KMS or whatever is true. So my question now is: can Gentoo do this? Surely so. Presumably it is just a matter of having the right kernel. Here is my config. What must I add, or remove, to achieve Mint's success with Gentoo?
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Michael Mounteney

Jaglover · Posted: Tue Nov 17, 2020 8:11 am Post subject:

Is Mint even using nVidia GPU? It probably is utilizing only Intel. No telling without looking at full Xorg log. In case it is using nVidia then where is located the xorg.conf it is using is also in Xorg log. To conclude, examine carefully Xorg log in Mint, quite likely all answers are there.
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My Gentoo installation notes.
Please learn how to denote units correctly!

mounty1 · l33t Joined: 06 Jul 2006 Posts: 955 Location: Queensland

It has to use the nVidia GPU to drive the external monitors. The first thing I did was check Xorg.0.log and that's how I knew it wasn't using an xorg.conf.
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Michael Mounteney

Jaglover · Posted: Tue Nov 17, 2020 8:44 am Post subject:

Mint has its own pastebin utility, care to pastebin its Xorg log? It may be possible it uses Nouveau without xorg.conf.
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My Gentoo installation notes.
Please learn how to denote units correctly!

NeddySeagoon · Posted: Tue Nov 17, 2020 11:18 am Post subject:

mounty1,

That's not Optimus. With Optimus, the nVidia GPU has no connections to any displays at all.

I am aware of a few strange laptops were its possible to set Optimus, if you only use the laptop screen or to only set nVidia and use external displays.
I have never had the opportunity to play with one.
It sounds like you have one of those.
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Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

mounty1 · l33t Joined: 06 Jul 2006 Posts: 955 Location: Queensland

It does use Nouveau! I must admit that I had never considered that, since I understood that Nouveau did not handle the more difficult sets of hardware but Nouveau is what it is using. So now, do I just keep using Mint or do I go back and replace the Nvidia drivers on my Gentoo installation with Nouveau? I'll do the latter whilst thinking about the former. Thanks for your reply. I won't mark the post as [SOLVED] until I have gotten Nouveau working though.
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Michael Mounteney

NeddySeagoon · Posted: Tue Nov 17, 2020 12:40 pm Post subject:

mounty1.

Unless something has changed, Xorg only autoconfigures the open source drivers.
xorg-drivers will not be considered.

Its a GPL2 licence infringement to distribute a binary kernel with the nvidia-drivers kernel module pre linked.
The nvidia-drivers kernel module sources are not available. The plug was pulled on kororaa for doing just that.
Its OK for users to do the linking. Thus installing nvidia-drivers on a binary distro always involves user action.

nouveau will work on Gentoo.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

mounty1 · l33t Joined: 06 Jul 2006 Posts: 955 Location: Queensland

Conclusion to the above: after a few more experiments, I've switched to NixOS on the laptop, which works on all three screens. It kind-of makes sense anyway, since the laptop is for work purposes and isn't part of my 'home' system, which is set up with a shared NFS-mounted /usr/portage, /usr/src etc. to manage portage configuration centrally. Yes, sure, it would be satisfying to get it working with Gentoo again but I have to pick my battles.

Thanks as always to Neddy for his help.
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Michael Mounteney