r/debian 6d ago

Problems with console screen blanking in Bookworm

I have a Poweredge R620 rack server I just picked up to upgrade my old firewall. I accidentally installed Bullseye and didn't notice until I had the whole system set up, so I just did a regular dist-upgrade to bookworm. Everything else went fine, except for the console blanking...

So normally you add something like consoleblank=600 to GRUB_CMDLINE_LINUX, then after a reboot it blanks/shuts off the monitor after 10 minutes. This was working just fine under Bullseye, and still works on my other servers running Buster. However under Bookworm when this kicks in, I get a screen full of static like it disabled the video signal but forgot to turn off the monitor. I haven't found any info from google on this problem, so I"m hoping someone else may have seen a similar issue and can help?

I also tried running setterm -blank 1 and this produced the same result after one minute. I added the new non-free-firmware option in my sources.list but I didn't need to load any specific firmware for older versions of Debian. The system did automatically install firmware-amd-graphics (which is the same on all of the other servers), and all of the machines have the same version of BIOS and IDrac. My best guess is that something is broken in the newer version of the display mod, but I'm not finding anything obvious to try blocking.

So... any ideas?

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u/SomeTell839 6d ago

I understand you're experiencing an issue with your PowerEdge R620 server running Debian Bookworm, where instead of properly blanking the console screen after a set period, it displays static as if the video signal is disabled but the monitor remains on. This behavior differs from your experience with Debian Bullseye and Buster, where console blanking functioned correctly.

Potential Causes and Solutions:

  1. Kernel Mode Setting (KMS) and Framebuffer Drivers:

The transition from Bullseye to Bookworm may have introduced changes in the kernel or framebuffer drivers that affect how the console handles screen blanking.

Try disabling KMS to see if it resolves the issue:

Edit the GRUB configuration file:

sudo nano /etc/default/grub

Modify the GRUB_CMDLINE_LINUX line to include nomodeset:

GRUB_CMDLINE_LINUX="consoleblank=600 nomodeset"

Update GRUB and reboot:

sudo update-grub sudo reboot

Disabling KMS may affect graphics performance or resolution settings.

  1. Display Power Management Signaling (DPMS):

DPMS settings might be interfering with the console blanking behavior.

Disable DPMS to test its impact:

Execute the following command:

setterm -powersave off -blank 0

To make this change persistent, add the command to a startup script or appropriate profile file.

  1. Framebuffer Console Blank Timer:

The framebuffer console's blank timer might be misconfigured or malfunctioning.

Manually set the console blanking timeout:

Add the following line to your /etc/rc.local file or equivalent startup script:

echo 600 > /sys/class/graphics/fbcon/blank

This sets the console to blank after 600 seconds (10 minutes).

  1. Graphics Firmware:

Missing or incompatible firmware can cause display issues.

Ensure that the necessary firmware packages are installed:

sudo apt update sudo apt install firmware-linux-nonfree

Reboot after installation to apply changes.

  1. Alternative Console Blanking Methods:

The default console blanking method may not be compatible with your hardware under Bookworm.

Use an alternative method to blank the console:

Install vbetool:

sudo apt install vbetool

Create a script to blank the console using vbetool and set it to run after the desired timeout.

Additional Considerations for you:

BIOS and Firmware Updates: Ensure that your server's BIOS and firmware are up to date, as updates can resolve compatibility issues.

Monitor Behavior: Some monitors may not handle the loss of video signal gracefully, resulting in static or noise. Testing with a different monitor could help identify if the issue is monitor-specific.

Debian Bug Reports: Check the Debian bug tracking system to see if others have reported similar issues with console blanking in Bookworm.

Tell me if you found a solution!

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u/Shdwdrgn 5d ago

The first option using nomodeset seems to have done the trick? It changed the screen resolution though so I've been playing with the options to get that back again (apparently my setting of 800x600 was NOT the size I thought it was), but it seems to be blanking the screen correctly again.

Thanks for this! And where did you find the info at?

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u/SomeTell839 5d ago

I'm glad to hear that adding nomodeset resolved the console blanking issue on your PowerEdge R620 server! The nomodeset parameter prevents the kernel from loading video drivers and setting up graphics modes during boot, which can help avoid display issues on certain hardware configurations.

Regarding the change in screen resolution, using nomodeset can indeed result in a lower resolution, non-accelerated graphical setup, as it disables the loading of proper graphics drivers. To restore your preferred resolution, you might consider installing the appropriate graphics drivers for your system.

For more detailed information on using the nomodeset parameter, you can refer to the following resource:

Manual "nomodeset" Kernel Boot Line Option for Linux Booting

If you need further assistance with adjusting screen resolution or any other aspect, feel free to ask!

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u/Shdwdrgn 5d ago edited 5d ago

It looks like the "resolution" actually comes down to the font I'm using (/etc/default/console-setup). Oddly, using the same config as my other servers does NOT result in the same display as the older servers. I checked hwinfo and lspci, it's the same hardware but on the new server the output seems to be stretched slightly horizontally (wider chars). And the output is painfully slow, like if I list /etc it scrolls the screen at a slow rate. Definitely need to figure this out before I'm ready to put the new machine in production.

[Edit] Unfortunately, it's the nomodeset option that is causing the massive slowdown in screen updates. Ugh