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#1 2021-08-31 16:52:49

atk91
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Registered: 2021-08-31
Posts: 7

Intel Graphics: boot hangs when two monitors are plugged in

If I add "debug" kernel paramenter, last thing I see is

fb0: switching to inteldrmfb from EFI VGA

After this system becomes irresponsible, I cannot even ctrl-alt-F* to text console.
However, I can still ssh into my system, and I see that systemd-udevd utilizes 100% of CPU.
I can also boot and login with nomodeset, and systemd-udevd behaves fine.

This started to happen a few weeks ago, after some kernel update. I then switched to linux-hardened, which was 5.12.19 at that moment, that helped, system started to boot just fine again.
Recently it was bumped to 5.13.13, so I cannot boot with it now.

I use GRUB with EFI, Intel Corporation RocketLake-S GT1 [UHD Graphics 750] (rev 04), Linux 5.13.13.hardened1-1

Any help or ideas of what's going on and how to fix it will be much appreciated.

UPD: I have tried to unplug DP monitor and it boots fine with only HDMI one, so I cannot boot with two monitors no matter how they are connected. The issue does not seem to be specific to HDMI.

UPD2: I can boot with two monitors (almost) if I do the following:
1) Unplug second one
2) Turn the power on, wait till grub prompt (it will be displayed only on one monitor since second is plugged off)
3) Plug in the second monitor
4) Press enter, then it boots fine

Last edited by atk91 (2021-09-01 11:16:40)

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#2 2021-09-23 10:41:07

atk91
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Registered: 2021-08-31
Posts: 7

Re: Intel Graphics: boot hangs when two monitors are plugged in

The issue still persists in Linux 5.14.6.hardened1-1
Looks like some kind of video mode which GRUB sets when discovers two monitors started to break some kernel's video routines.

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#3 2021-09-23 13:20:28

CarbonChauvinist
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Registered: 2012-06-16
Posts: 412
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Re: Intel Graphics: boot hangs when two monitors are plugged in

Do you have `xf86-video-intel` package installed? If so try removing (and any .conf files that reference the "intel" driver) in order to fall back to modesetting DDX driver.

Also if you haven't already, try enabling early KMS

I'd also suggest moving away from the hardened kernel unless you have some real specific reason for using (other than just trying to avoid this issue).

Those are usually two low hanging fruit to try before delving into more in-depth troubleshooting.


"the wind-blown way, wanna win? don't play"

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#4 2021-09-23 14:03:44

seth
Member
Registered: 2012-09-03
Posts: 49,984

Re: Intel Graphics: boot hangs when two monitors are plugged in

"xrandr -q"?
Try to enforce modes w/ https://raw.githubusercontent.com/torva … modedb.rst

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#5 2021-09-27 12:36:41

atk91
Member
Registered: 2021-08-31
Posts: 7

Re: Intel Graphics: boot hangs when two monitors are plugged in

seth wrote:

"xrandr -q"?
Try to enforce modes w/ https://raw.githubusercontent.com/torva … modedb.rst

This is the output when I unplug one monitor, plug it back when GRUB prompt appears after which it boots successfully

$ xrandr -q
Screen 0: minimum 320 x 200, current 3840 x 1080, maximum 16384 x 16384
HDMI-1 disconnected (normal left inverted right x axis y axis)
HDMI-2 connected 1920x1080+1920+0 (normal left inverted right x axis y axis) 5
   1920x1080     60.00*+  50.00    59.94  
   1920x1080i    60.00    50.00    59.94  
   1600x1200     60.00  
   1600x900      60.00  
   1280x1024     75.02    60.02  
   1152x864      75.00  
   1280x720      60.00    50.00    59.94  
   1024x768      75.03    60.00  
   800x600       75.00    60.32  
   720x576       50.00  
   720x576i      50.00  
   720x480       60.00    59.94  
   720x480i      60.00    59.94  
   640x480       75.00    60.00    59.94  
   720x400       70.08  
DP-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis
   1920x1080     60.00*+  50.00    59.94  
   1920x1080i    60.00    50.00    59.94  
   1600x1200     60.00  
   1600x900      60.00  
   1280x1024     75.02    60.02  
   1152x864      75.00  
   1280x720      60.00    50.00    59.94  
   1024x768      75.03    60.00  
   800x600       75.00    60.32  
   720x576       50.00  
   720x480       60.00    59.94  
   640x480       75.00    60.00    59.94  
   720x400       70.08  
HDMI-3 disconnected (normal left inverted right x axis y axis)

I have enabled early KMS by MODULES=(i915) in /etc/mkinitcpio.conf, xf86-video-intel is not installed.

Did I understand correctly that in order to enforce video mode I need to add kernel parameter, e.g.

GRUB_CMDLINE_LINUX="video=DP-1:1920x1080@60me video=HDMI-2:d"

in /etc/default/grub and then

grub-mkconfig -o /boot/grub/grub.cfg

?

Last edited by atk91 (2021-09-27 12:42:16)

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#6 2021-09-27 15:11:45

seth
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Registered: 2012-09-03
Posts: 49,984

Re: Intel Graphics: boot hangs when two monitors are plugged in

Did I understand correctly

For instance, but I'd strongly recommend to edit the kernel commandline interactively in grub (select the kernel you want to boot and press "e") - if this goes wrong, the mode selection will then implicitly be lost w/ a reboot.

I could imagine that the interlaced mode is falsely selected.

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#7 2021-09-27 15:26:06

atk91
Member
Registered: 2021-08-31
Posts: 7

Re: Intel Graphics: boot hangs when two monitors are plugged in

I have tried to boot with these kernel parameters, no difference. However I still got kernel debug messages on both screens, isn't "video=DP-1:1920x1080@60me video=HDMI-2:d" supposed to disable one monitor?

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#8 2021-09-27 15:46:31

seth
Member
Registered: 2012-09-03
Posts: 49,984

Re: Intel Graphics: boot hangs when two monitors are plugged in

isn't "video=DP-1:1920x1080@60me video=HDMI-2:d" supposed to disable one monitor?

Yes.
Is there anything interesting in the journal for a failing boot? (i915/drm/intel errors)?

To be sure: there's no second GPU?

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#9 2021-09-27 16:36:28

atk91
Member
Registered: 2021-08-31
Posts: 7

Re: Intel Graphics: boot hangs when two monitors are plugged in

There's no second GPU.

I can't find any boot entries for failed boot in "journalctl --list-boots" - they are only succesful ones, either with unplugged monitor or nomodeset. I noticed that I can't anymore ssh into machine when this error occurs.

As for console output, this is what I see with debug kernel parameter, nothing is about i915, drm or intel errors, I guess

Last edited by atk91 (2021-09-27 16:37:48)

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#10 2021-09-27 16:46:19

seth
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Registered: 2012-09-03
Posts: 49,984

Re: Intel Graphics: boot hangs when two monitors are plugged in

i915.enable_fbc=0

https://wiki.archlinux.org/title/Intel_ … nable_fbc)

Can you force other modes, eg. 800x600?

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#11 2021-09-27 16:58:24

atk91
Member
Registered: 2021-08-31
Posts: 7

Re: Intel Graphics: boot hangs when two monitors are plugged in

No difference, except one line "Setting dangerous option enable_fbc - tainting kernel"

Can you force other modes, eg. 800x600?

I can, but I don't think they're being set, because this console output is exactly in the same resolution which I specify to GRUB in GRUB_GFXMODE. Looks like the mode has to be switched after that 'switching to inteldrmfb from efi vga'

If that matters, these values for GRUB are

# The resolution used on graphical terminal    
# note that you can use only modes which your graphic card supports via VBE    
# you can see them in real GRUB with the command `vbeinfo'    
GRUB_GFXMODE=1920x1080x32    
    
# Uncomment to allow the kernel use the same resolution used by grub    
GRUB_GFXPAYLOAD_LINUX=1920x1080x32 

Forgot to mention that's it's even impossible to boot with two monitors from Arch Live USB since when it's kernel became recent enough, it does not use grub, so I don't think issue is specific to grub.

Looks like I'm not the only one with that problem, just found this issue.

Last edited by atk91 (2021-09-27 17:12:16)

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#12 2021-09-28 07:11:16

seth
Member
Registered: 2012-09-03
Posts: 49,984

Re: Intel Graphics: boot hangs when two monitors are plugged in

Comment those, especially the second one.
However the fdo reporter runs 800x600 => 1400x900 so I'd not hold my breath…

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#13 2021-10-30 23:47:00

t0ssox
Member
Registered: 2021-10-30
Posts: 1

Re: Intel Graphics: boot hangs when two monitors are plugged in

Are you using monitor with native DP monitor or one with dodgy DP converter? It's still a issue for you or you found workaround? Can you test boot with second monitor using monitor connected to USB-C via some adapter?

Last edited by t0ssox (2021-10-30 23:48:33)

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#14 2021-10-31 18:20:13

makem
Member
Registered: 2016-12-21
Posts: 4

Re: Intel Graphics: boot hangs when two monitors are plugged in

I have the same problem and am using the DP port for my primary monitor. I have tried many things including a live USB.

With the live USB the HDMI monitor does not get a signal.

With the DP port only connected the system works fine using the kernel 5.13 prior to which I only had software rendering.

Even with the HDMI monitor turned off the system hangs in grub and in windows. I must removed the HDMI cable and reboot.

I am beginning to wonder if the mobo supports two monitors. Intel say their drivers do but we are talking about hardware and Ubuntu not windows.

Your latest update is also what I found. This suggests the mobo may support two and it maybe the Ubuntu driver at fault. When I use this method the HDMI monitor takes over the complete desktop and my 'best' monitor  becomes either a duplicate or a slave. The Display setting has no effect except duplicating the displays.

I have posted an issue:

https://github.com/intel-gpu/documentation/issues/26

Where I obtained help to get the drivers updated to ensure the correct driver was being installed (i915?)

Last edited by makem (2021-10-31 18:54:04)

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#15 2022-02-07 09:56:38

atk91
Member
Registered: 2021-08-31
Posts: 7

Re: Intel Graphics: boot hangs when two monitors are plugged in

Hey everyone! Looks like that issue was finally fixed:
https://gitlab.freedesktop.org/drm/inte … te_1248016

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