On Tuesday, 25 June 2024 19:54:33 BST Dale wrote:
> Michael wrote:

> > You need to have USE="elogind -systemd" in your make.conf, then add the
> > elogind service to the *boot* runlevel as shown here:
> > 
> > https://wiki.gentoo.org/wiki/Elogind
> 
> I read down through that.  I did find that acl had made it into the USE
> flag line.  I removed it.

You shouldn't have.


> It's not on my main rig so no idea where that
> came from.

It is enabled by the profile defaults:

~ $ euse -I acl
global use flags (searching: acl)
************************************************************
[+ CD   ] /var/db/repos/gentoo/profiles/use.desc:acl - Add support for Access 
Control Lists
[snip ...]


> > Can you please save and attach as plain text files your:
> > 
> > 1. dmesg
> > 2. Xorg.0.log
> > 3. ~/.local/share/sddm/xorg-session.log
> > 4. /var/log/sddm.log
> > 
> > after you end up in a black screen, in case they reveal something.
> 
> Should be attached.  I blanked the files and then rebooted and started
> display-manager, (DM).  You should have only the most recent info.  I'm
> also putting a chunk of messages below.  It might help.  It isn't much. 
> Same as before it seems.  I still say this is something simple but hard
> to find.  :/ 
> 
> Dale
> 
> :-)  :-) 
> 
> Messages:
[snip ...] 

> Jun 25 13:31:18 Gentoo-1 kernel: nvidia-modeset: WARNING: GPU:0: Unable
> to read EDID for display device DP-3

The above message indicates the same problem you had experienced before you 
reinstalled.  The monitor is not sending its EDID table, or the card can't 
read it.

Your Xorg sets a default dummy resolution of 640 x 480, because it can't find 
anything connected to the card.

Things I would try, until someone who can grok nvidia contributes better 
ideas:

Eliminate the hardware being the cause of the problem, e.g.: try a different 
cable, different monitor, then try the same card (with same drivers and same 
kernel settings) on your other PC.  If this proves there's nothing wrong with 
the cable, card, or kernel settings:

1. Try different ports and restart display-manager each time.

2. Add these two lines at the bottom of /usr/share/sddm/scripts/Xsetup:

xrandr --setprovideroutputsource modesetting NVIDIA-0
xrandr --auto

Again restart display-manager.

3. Add a file /etc/X11/xorg.conf.d/20nvidia.conf

Section "Device"
   Identifier  "nvidia"
   Driver      "nvidia"
   BusID       "PCI:9:0:0"
   Option "UseEDID" "false" ## Try this too ##
EndSection

Again restart display-manager.

Every time you try a setting and it doesn't produce the goods, revert it 
before you try the next thing.  Make notes and keep an eye on your logs in 
case you spot a difference.

If none of these tweaks work, then you can try capturing the EDID table and 
creating a file for the card to load.

HTH.