LinuxCNC 2.9.2 Pi 5 Debian Bookworm hdmi_force_hotplug not working

[dqrw]

Here are the steps I follow to reproduce the issue:

This looks to be a Bookworm issue but not sure how to submit that issue since this OS is specific to LinuxCNC.

Setup to run Pi 5 LinuxCNC in headless configuration.

1. Set hdmi_force_hotplug=1 in boot/config.txt
2. Install x11vnc and setup to startup with systemctl
3. Setup to auto login in.
4. Setup for wireless connectivity.
5. Disable login timeout (never logout)
6. Power down and remove all cables.
7. Plug in power.
8. Make sure you can ping from client.
9. VNC into server with TigerVNC or equivalent.

This is what I expected to happen:

I would expect to connect and be prompted for a password and to enter proper password. Then to be connected and see full display.

This is what happened instead:

The client could connect and was not prompted for the password. The configuration works with a HDMI connection but is supposed to work without a display connected.

The setup also works properly without a HDMI monitor using the current Raspberry Pi OS.

Information about my hardware and software:

LinuxCNC 2.9.2 Pi 5 Debian Bookworm

Raspberry Pi 5 8 GB RAM. 256 GB NVme SSD.

Booted from both SSD and Micro SD card when testing.