[CALUG] Looking for advice

[Dave Dodge]

On Wed, Feb 13, 2019 at 12:09:45AM -0500, Tim Spangler wrote:
> Out of box Fedora 29 Desktop handles the nvidia cards with the nouveau driver,
> and I can confirm it works fine with a single monitor at 2560x1600 resolution

Just another data point: Xubuntu 18.04.2 LTS with the nouveau driver,
I currently have a 3440x1440 main monitor and a (rotated) 1440x2560 on
the side. I've run three monitors in the past using an AMD card. At
work we have CentOS desktops with four monitors, possibly with the
nouveau driver as well but I'm not sure.

I've gone back and forth many times between AMD vs. NVIDIA and free
vs. proprietary drivers. I don't think any particular combination is
going to be perfect all the time and I've hit bugs in all combinations
where pixels are glitching or video playback stops working or the
screen goes blank and the system freezes, etc. A reboot gets things
back in order.

The current nouveau driver seems pretty stable for desktop use (I can
stay logged in for weeks at a time) *but* it doesn't have CUDA
support, so if you want to play around with that you have to go
proprietary. In order to rotate one of the displays I ended up
configuring the desktop session to run a little xrandr script from my
home directory, so while it's fine once I'm logged in, the login
prompt itself still shows up sideways.

On Tue, Feb 12, 2019, 16:10 Tim Spangler <tspang at jefnet.com <mailto:tspang at jefnet.com>  wrote:
> That said, trying to blacklist one of them and using PCI Express
> Pass through to have direct access from a KVM VM is proving to quite
> be challenging.

When I went down that road several years ago the biggest problem was
the NVIDIA proprietary driver. NVIDIA only supported virtualization on
their expensive Quadro cards and their driver *actively enforced* this
by disabling gaming cards if it detected that it was running in a VM.
I was trying to build a system with good gaming support on both the
Linux host and the Windows guest, so the proprietary driver was
needed.

I did manage to pass through an AMD card to a Windows guest and it
seemed to work fine, but I still had issues with NVIDIA on the host
side because of a separate set of bugs when using their driver under
the Xen kernel. I finally gave up and just built a separate Windows
machine.

A person I talked to at the time was successfully able to pull it off
but had to go to some extreme lengths: he had a low-end AMD card with
good free driver support for the host, and then passed through two GTX
cards to guests (one Linux, one Windows). He modified the cards with a
soldering iron so that they'd report the ID of a Quadro card that used
the same GPU chip, and that was enough to trick the driver into
accepting them.

                              -Dave Dodge/dododge at dododge.net