[Bug 2060268] Re: Phantom "Unknown Display" shown in Settings after installing the Nvidia driver

> I also have encryption, does everyone with the bug have it?


Nope. I just got my bug marked duplicate here. I am not running encryption, but I am running ZFS, which uses a vaguely similar disk abstraction (booting a "fake" device that "maps" to a real one in some arbitrary way).

However, my bug was solved when I installed kubuntu-desktop (and then
switched the default display manager back to gdm3). So, I assume one of
the dependencies it brought along fixed it.

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https://bugs.launchpad.net/bugs/2060268

Title:
Phantom "Unknown Display" shown in Settings after installing the
Nvidia driver

Status in linux package in Ubuntu:
Confirmed
Status in nvidia-graphics-drivers-470 package in Ubuntu:
Confirmed
Status in nvidia-graphics-drivers-535 package in Ubuntu:
Confirmed
Status in nvidia-graphics-drivers-545 package in Ubuntu:
Confirmed
Status in nvidia-graphics-drivers-550 package in Ubuntu:
Confirmed

Bug description:
[ Impact ]

After installing Nvidia driver 545 on a single (27") monitor system,
Settings shows a phantom 46" monitor of the same resolution.

It looks like the phantom monitor is /dev/dri/card0 which is still
controlled by simpledrm, while Nvidia uses /dev/dri/card1.

[ Temporary Workaround ]

1. sudo rm /dev/dri/card0
2. Log in again.

[ Permanent Workaround ]

Add kernel parameter:
initcall_blacklist=simpledrm_platform_driver_init

[ Test Plan ]

Open Settings and verify the only monitors shown are your real
monitors.

[ Where problems could occur ]

Removing the simpledrm card is only safe when it's not being used. If
somehow a machine wasn't using the installed Nvidia driver then there
could be a risk of deleting the only working display.

[ Other Info ]

ProblemType: Bug
ApportVersion: 2.28.0-0ubuntu1
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/seq: dan 4631 F.... pipewire
 /dev/snd/controlC1: dan 4636 F.... wireplumber
CRDA: N/A
CasperMD5CheckResult: pass
DistroRelease: Ubuntu 24.04
InstallationDate: Installed on 2024-01-04 (92 days ago)
InstallationMedia: Ubuntu 24.04 "Noble Numbat" - Daily amd64 (20231127)
MachineType: Intel(R) Client Systems NUC12DCMi7
NonfreeKernelModules: nvidia_modeset nvidia
Package: linux (not installed)
ProcEnviron:
 LANG=en_US.UTF-8
 PATH=(custom, no user)
 SHELL=/bin/bash
 TERM=xterm-256color
 XDG_RUNTIME_DIR=<set>
ProcFB: 0 simpledrmdrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.8.0-11-generic root=UUID=8434774e-88f2-4e3f-adb8-2eb07dff3cf9 ro quiet loglevel=3 splash vt.handoff=7
ProcVersionSignature: Ubuntu 6.8.0-11.11-generic 6.8.0-rc4
RelatedPackageVersions:
 linux-restricted-modules-6.8.0-11-generic N/A
 linux-backports-modules-6.8.0-11-generic N/A
 linux-firmware 20240318.git3b128b60-0ubuntu1
Tags: noble
Uname: Linux 6.8.0-11-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin plugdev sudo users
_MarkForUpload: True
dmi.bios.date: 12/20/2021
dmi.bios.release: 5.24
dmi.bios.vendor: Intel Corp.
dmi.bios.version: EDADL579.0046.2021.1220.2351
dmi.board.name: NUC12EDBi7
dmi.board.vendor: Intel Corporation
dmi.board.version: M27908-302
dmi.chassis.type: 35
dmi.chassis.vendor: Intel Corporation
dmi.chassis.version: 2.0
dmi.ec.firmware.release: 3.7
dmi.modalias: dmi:bvnIntelCorp.:bvrEDADL579.0046.2021.1220.2351:bd12/20/2021:br5.24:efr3.7:svnIntel(R)ClientSystems:pnNUC12DCMi7:pvrM30143-302:rvnIntelCorporation:rnNUC12EDBi7:rvrM27908-302:cvnIntelCorporation:ct35:cvr2.0:skuRNUC12DCMi70000:
dmi.product.family: DC
dmi.product.name: NUC12DCMi7
dmi.product.sku: RNUC12DCMi70000
dmi.product.version: M30143-302
dmi.sys.vendor: Intel(R) Client Systems

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