Hello:

On 30 Jun 2024 at 21:33, Ralph Ronnquist wrote:

> ... little confused about what you say here.
Because it probably *is* confusing ... 8^)
Sorry ...

Let's se if I can make it less so.

If I do not use an xorg.conf file, xorg/nouveau works.
Almost out of the box, so to speak.

After much poking around, I managed to figure out that what xorg was
'automagically configuring' was a 3840x1024 screen without using
Xinerama by (no idea how) getting the two cards to work at the *same*
time with the three monitors.

This (apparently) some correlation to how the Nvidia driver's
"BaseMosaic" option works to "extend a single X screen transparently
across display outputs on each GPU." without a video bridge between
the cards.

See here:
https://bbs.archlinux.org/viewtopic.php?pid=1709740#p1709740

So I went about writing up a 10-monitor.conf file, dropped it in
the /etc/X11/xorg.conf.d/ directory and restared the xserver.

The end result was the same with and without it being there.

At this point, xorg was using the
/etc/X11/xorg.conf.d/10-monitor.conf at boot time.

See here to see the screen layout and the three "Monitor" sections
used.

https://dev1galaxy.org/viewtopic.php?pid=50730#p50730

I then renamed 10-monitor.conf to 10-monitor.test, wrote up a
etc/X11/xorg.conf with the same content and restarted the xserver.

The end result was the same with as when the 10-monitor.conf file was
being used.

At this point, xorg was using the /etc/X11/xorg.conf file at boot
time.

It was quite clear (to me) that the xorg.conf file, at least with
respect to the "Monitor" sections, was working correctly.

When I tried (whichever way) to generate a complete xorg.conf file,
what I got was a configuration that *did not* do the same that xorg
did when booting.

--------
Section "Monitor"
         Identifier         "Monitor0"
         VendorName  "Monitor Vendor"
         ModelName    "Monitor Model"
EndSection

Section "Monitor"
         Identifier          "Monitor1"
         VendorName   "Monitor Vendor"
         ModelName     "Monitor Model"
EndSection
--------
ie: only two monitors.

I have read comments all over the web saying that xorg -configure has
not worked properly for the longest time, so I was not surprised.

Hope I cleared things up.

Thank you very much for your input.

Best,

A.