raspberry pi doesn't boot without monitor attached

[lheckemann]

Describe the bug
The 19.09 and unstable aarch64 sd images won't boot on the raspberry pi 3A+ (checked myself) and 3B+ (I think I heard this) if no monitor is connected to its HDMI port.

To Reproduce
Steps to reproduce the behavior:

1. Write 19.09 or unstable sd image to SD card
2. Insert SD card in raspberry pi
3. Power up with no monitor attached

Expected behavior
Boots.

Actual behaviour
Boot loop, where u-boot repeatedly resets when trying to initialise the graphical console.

Additional context
This works if the firmware in the pi boot partition is replaced with raspberrypifw from 19.03.

Maintainer information:

# a list of nixpkgs attributes affected by the problem
attribute: raspberrypifw
# a list of nixos modules affected by the problem
module:

cc @mmahut who I believe had this issue too.

[alexbakker]

I'm facing the same issue. This can also be worked around by setting hdmi_force_hotplug=1 in config.txt.

[kwohlfahrt]

Can confirm this on the 3B (not plus), and that the workaround above fixes it. I'll see if I can debug more, is there any upstream report?

For my notes: The earliest nixpkgs version I can confirm this was 30127503a5edd2da66f889e39e2c9b000d11a1bf, and 19.03 was still OK.

[hexop]

I have a 3B (not plus), and I tried the workaround adding:

boot.loader.raspberryPi.firmwareConfig = ''
    hdmi_force_hotplug=1
  '';

But it still doesn't boot if there's no HDMI plugged in. I have to add that I'm an absolute newbie to NixOS and I just set up the machine.

[craigem]

What happens if you write /boot/config.txt manually, @hexop ?

I've found that firmwareConfig appears to be broken in 19.09 (see #67792 ).

[hexop]

What happens if you write /boot/config.txt manually, @hexop ?

I've found that firmwareConfig appears to be broken in 19.09 (see #67792 ).

Well I've tried creating /boot/config.txt manually, and it still doesn't work. I've also tried removing the boot.loader.raspberryPi.firmwareConfig from configuration.nix but it still doesn't work.
Right now I have plugged an HDMI-to-VGA converter in the HDMI port and it powers on, without the need for a real monitor.

[alexbakker]

Try mounting mmcblk0p1 and changing the config.txt that's there, instead of the one on mmcblk0p2.

[hexop]

Try mounting mmcblk0p1 and changing the config.txt that's there, instead of the one on mmcblk0p2.

That worked perfectly! Thank you so much.

[stale]

Hello, I'm a bot and I thank you in the name of the community for opening this issue.

To help our human contributors focus on the most-relevant reports, I check up on old issues to see if they're still relevant. This issue has had no activity for 180 days, and so I marked it as stale, but you can rest assured it will never be closed by a non-human.

The community would appreciate your effort in checking if the issue is still valid. If it isn't, please close it.

If the issue persists, and you'd like to remove the stale label, you simply need to leave a comment. Your comment can be as simple as "still important to me". If you'd like it to get more attention, you can ask for help by searching for maintainers and people that previously touched related code and @ mention them in a comment. You can use Git blame or GitHub's web interface on the relevant files to find them.

Lastly, you can always ask for help at our Discourse Forum or at #nixos' IRC channel.

[Dietr1ch]

I just lost a couple of hours debugging this without a monitor around my RPi 4B.

The fix is still temporarily mounting /dev/mmcblk0p1 to edit config.txtand adding hdmi_force_hotplug=1 in part of the config that would be loaded (I used the RPi4-specific section).

[stale]

I marked this as stale due to inactivity. → More info

[rambip]

Exact same issue with a raspberrypi 4.

I added manually the line hdmi_force_hotplug=1 to /boot/config.txt and it works.

A solution where this file is generated by nix would be nice, but the boot.loader.raspberrypi.firmwareConfig option does not seem to generate /boot/config.txt, the manual fix was ghe only thing that worked.

Is there a better fix now ?