Thinkpad X11 — HDMI display cloning works only for the original user account

Distribution

Mint 22.3

Package version

Cinnamon 6.6.9

Graphics hardware in use

Intel Corporation TigerLake-LP GT2 [Iris Xe Graphics]

Frequency

Always

Bug description

Linux Mint 22.3 / Cinnamon / X11 — HDMI display cloning works only for the original user account
Configuration
• ThinkPad X1 Yoga Gen 6
• Linux Mint 22.3
• Cinnamon / X11
• Intel graphics
• Internal display + interactive whiteboard (IWB) connected via HDMI
• eDP-1 = internal display
• HDMI-1 = IWB
Problem
Display cloning works for only one user account, admin1, and fails for every other account tested.
• admin1 — UID 1000 — /home/admin1 → CLONING WORKS
• admin2 — UID 1001 — /home/admin2 → CLONING FAILS
• testadmin — newly created administrator account → CLONING FAILS
• testadmin2 — newly created account with the same groups as admin1 → CLONING FAILS
With admin2:
• the IWB is correctly detected;
• extended desktop works;
• xrandr correctly detects both displays;
• the "Clone" option is available;
• but when cloning is enabled, the display flickers/goes black and does not stabilize.
Both displays support a common mode of 1920×1080 @ 60 Hz.
Direct cloning with xrandr was also tested:
xrandr --output eDP-1 --mode 1920x1080
--output HDMI-1 --mode 1920x1080 --same-as eDP-1
→ same failure.
User/account tests
The problem does not appear to be simply related to administrator privileges.
• admin1 — administrator, created during the Mint installation → cloning works
• admin2 — originally a normal user, later promoted to administrator → cloning fails
• testadmin — newly created administrator account → cloning fails
• testadmin2 — newly created account with the same groups as admin1 → cloning fails
Groups:
admin1 : adm cdrom sudo dip plugdev users lpadmin sambashare
admin2 : adm cdrom sudo dip plugdev users kvm lpadmin sambashare
There was initially a session issue with testadmin: after adding it to the sudo group, its already-running graphical session had not inherited the new group.
The session was fully terminated using:
loginctl terminate-user testadmin
and a new session was started.
All subsequent checks were therefore performed after a complete logout/login.
Test on a fresh installation
A clean Linux Mint 22.3 installation was then performed on a separate partition, in order to test whether the problem was caused by some user-specific or system-specific configuration.
On this new installation:
• only one work user was created;
• this user was the first user created during installation;
• its UID was 1000;
• the IWB was correctly detected;
• extended desktop works;
• but display cloning also fails.
This shows that the working behaviour of admin1 cannot be explained simply by UID 1000 or by being the first user created during installation.
Test with a second IWB
A second IWB of the same make and model was then tested.
Importantly, this second IWB had never previously been connected to this PC.
The test was started directly from the fresh Linux Mint 22.3 installation, which contains only one user with UID 1000.
Result:
• second IWB, never previously connected to the PC;
• fresh Linux Mint 22.3 installation;
• single user, UID 1000;
• IWB correctly detected;
• cloning → FAILS.
The behaviour is exactly the same as with the first IWB.
The second IWB was then also tested with the original installation:
• admin1 → CLONING WORKS
• other accounts → CLONING FAILS
The same behaviour is therefore reproduced with two identical IWBs.
This makes the following explanations very unlikely:
• a fault specific to the first IWB;
• a configuration remembered for the first IWB;
• an IWB connection/history issue;
• a video negotiation problem specific to one particular unit.
The HDMI cable hypothesis is also strongly weakened if the same cable was used for both tests.
Overall results
Original installation:
admin1 — UID 1000 → CLONING WORKS
admin2 — UID 1001 → CLONING FAILS
testadmin → CLONING FAILS
testadmin2 → CLONING FAILS

Linux Mint 22.3 Live USB → CLONING FAILS

Fresh Linux Mint 22.3 installation:
first and only user — UID 1000 → CLONING FAILS

Second identical IWB:
admin1 on original installation → CLONING WORKS
other users → CLONING FAILS
fresh installation / UID 1000 → CLONING FAILS
xrandr
On admin2, with the IWB connected:
eDP-1 connected primary
HDMI-1 connected
Typical extended configuration:
eDP-1 : 1920x1200 +0+0
HDMI-1 : 3840x2160 +1920+0
xrandr --listmonitors correctly reports two monitors.
Both the internal display and the IWB support 1920×1080 @ 60 Hz.
Other tests
• cinnamon --replace → no change
• default-monitors-setup = do-nothing → no change
• GNOME Boxes / Machines was not running during the recent tests
• spice-vdagent is not installed
• Linux Mint 22.3 Live USB also fails to clone
• the fresh Linux Mint 22.3 installation on a separate partition also fails to clone
A cross-test was also performed over two consecutive boots:
1. boot directly as admin2, cold start, with the IWB connected before login → cloning fails
2. switch user to admin1 on the same machine, without unplugging/replugging the IWB → cloning works
Particularly important point
The hardware, GPU, X11 server and graphics stack are capable of performing display cloning, because admin1 can clone the displays on the original installation using the same PC and the same IWB.
However, cloning fails:
• with every other user on the original installation;
• from the Linux Mint 22.3 Live USB;
• from a fresh Linux Mint 22.3 installation;
• with a single user whose UID is also 1000;
• with a second identical IWB that had never previously been connected to the PC.
Therefore, the issue does not appear to be simply related to:
• UID;
• Unix group membership;
• administrator privileges;
• a particular Mint installation;
• failure to detect the IWB;
• the first IWB;
• or the IWB's connection history.
Current conclusion / hypothesis
At this point, a hardware-related explanation has become very unlikely.
The behaviour is highly reproducible and appears to depend on the user/session environment.
The only known working environment is:
Original Linux Mint 22.3 installation
└── original user account admin1
└── HDMI cloning works
Every other tested environment fails.
This strongly suggests a software bug or software-specific behaviour in Linux Mint 22.3 / Cinnamon / Muffin / X11, potentially related to some user-specific configuration or state.
The exact cause remains unknown.
In particular, we still do not know what functionally distinguishes admin1 from the other users and allows cloning to work.
Question for developers
What could cause display cloning to behave differently depending on the user under Cinnamon/X11?
Could this be related to:
• per-user display configuration;
• Cinnamon/Muffin configuration;
• the user session environment;
• Polkit or session permissions;
• user configuration files;
• persistent state created during installation or during the first session;
• a graphics-stack component initialized differently for different users;
• or another per-user mechanism?
The main question is:
How can we identify what distinguishes the working admin1 environment from the failing environments, and how can display cloning be made to work on the work account?
Any method for systematically comparing the working admin1 environment with the failing user environments would be particularly helpful.
Current workaround
admin1 is currently the only environment in which cloning has been proven to work.
It is therefore being preserved as a reference environment and fallback solution.
A complete Mint reinstallation with the work account created as the first user is still being considered as a practical workaround. However, because a fresh installation with a first user having UID 1000 has already failed, this is not considered a guaranteed solution.

Steps to reproduce

Install Linux Mint 22.3 on a ThinkPad X1

• Test cloning an interactive whiteboard using this first profile.
• Then create a second “Normal” profile: The system detects the IWB and displays the clone button, but it is not possible to confirm the clone.

Expected behavior

On the X1, cloning a IWB should be possible from any Linux Mint profile.

Additional information

Important — Limited Availability for Further Testing
I currently have very limited access to the IWB and may not be able to perform extensive additional testing after this report is submitted.
I would therefore particularly appreciate either:
• a known workaround that could make display cloning work on my work account;
• a configuration change or command that I could try once the IWB is available;
• or, if possible, guidance on how to reproduce the working admin1 configuration on another user account.
I am happy to provide additional information that can be collected without an IWB, but extensive repeated tests with the hardware may not be possible.

Start by reproducing the account-dependent behavior described for Cinnamon/X11, comparing the working admin1 session with failing accounts. Use xrandr, xrandr --listmonitors, cinnamon --replace, and default-monitors-setup as the reported entry points. Done means identifying the session or configuration difference and making HDMI cloning work from other profiles.