How to fool a laptop into thinking a monitor is connected?

Hello! I converted an old laptop with a broken screen into a home server, and it all works well except for one thing: when I reboot it (via ssh), if no screen is connected, it will get stuck and refuse to boot. as soon as I connect an HDMI monitor, the fans will start spinning and it will start booting as usual. Then I can remove the HDMI and it will work flawlessly. I don’t know if this is a linux problem, a GRUB problem, or a firmware problem.
Any idea on how to solve this, or on how to fool it into thinking a screen is connected? The problem is not the lid switch as I removed the magnet from the screen, so it thinks the lid is always open

Thanks in advance!

sxan,
@sxan@midwest.social avatar

Is it getting stuck in the BIOS? If you can’t ssh in, can you even ping it? Network should come up before graphics.

Have you disabled the display manager?

As someone eles mentioned, boot it with a screen and check the BIOS. Since this was a laptop, the BIOS is certainly expecting a display, so you might have to adjust something there.

tubbadu,

Yes I can ping it!

Have you disabled the display manager?

yep, I did `systemctl set-default multi-user.target’

As someone eles mentioned, boot it with a screen and check the BIOS. Since this was a laptop, the BIOS is certainly expecting a display, so you might have to adjust something there.

I already looked into the bios but it was pretty empty, just a few options, nothing about displays or graphics card

but now I have a doubts, perhaps there is a “show advanced settings” button somewhere that I didn’t see? I have to look for it

breakingcups,

There might be settings in the bios that allow you to disable the graphics card, not halt on errors or disable the internal screen, but they’re not usually exposed on laptop BIOS, they’re quite locked down.

TheyCallMeHacked,

There are a few ways to investigate, but for that we would need a bit more info. Firstly, what distro do you use ? Try using a different bootloader than GRUB to see if it solves the issue. Otherwise you could also try to use Linux’s UEFI stub.

tubbadu,

So you think it’s a grub problem?

I’m running fedora 39

TheyCallMeHacked,

I don’t know what the problem is. I’m trying to rule things out one after the other.

Maybe try using systemd-boot instead of GRUB?

mofongo,

On windows I think you need a HDMI dummy plug as others mentioned here before but Linux has to have a way to run headless. You can run Linux in Qemu without a connected display. If you find anything on why it’s not booting please let me know!

FQQD,
@FQQD@lemmy.ohaa.xyz avatar

I think there are dummy hdmi plugs that act as a monitor, that might work

Frederic,

This, EDID dummy plug, $2 on aliexpress

tubbadu,

just ordered one XD

If I’ll find a better solution I’ll have wasted 1.67€

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