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Rob_H

Member

Registered: 2012-06-19

Posts: 72

SDDM fails on startup with: "Failed to read display number from pipe"

After upgrading my computer this weekend, SDDM (or, more precisely, X) fails to start at boot time. I'm using NVIDIA proprietary driver and hardware. If I run:

sudo journalctl  -b -u sddm.service

I see:

-- Logs begin at Tue 2020-05-26 19:11:26 EDT, end at Tue 2020-12-01 20:43:03 EST. --
Dec 01 20:39:14 iris systemd[1]: Started Simple Desktop Display Manager.
Dec 01 20:39:14 iris sddm[678]: Initializing...
Dec 01 20:39:14 iris sddm[678]: Starting...
Dec 01 20:39:14 iris sddm[678]: Logind interface found
Dec 01 20:39:14 iris sddm[678]: Adding new display on vt 1 ...
Dec 01 20:39:14 iris sddm[678]: Loading theme configuration from ""
Dec 01 20:39:14 iris sddm[678]: Display server starting...
Dec 01 20:39:14 iris sddm[678]: Adding cookie to "/var/run/sddm/{61e8f2cd-8fc7-4ae6-a1c4-09fa87863969}"
Dec 01 20:39:14 iris sddm[678]: Running: /usr/bin/X -nolisten tcp -auth /var/run/sddm/{61e8f2cd-8fc7-4ae6-a1c4-09fa87863969} -background none -noreset -displayfd 17 -seat seat0 vt1
Dec 01 20:39:15 iris sddm[678]: Failed to read display number from pipe
Dec 01 20:39:15 iris sddm[678]: Could not start Display server on vt 1

However, if I log into the console and restart SDDM, it comes up just fine the second time.

-- Logs begin at Tue 2020-05-26 19:11:26 EDT, end at Tue 2020-12-01 20:43:03 EST. --
Dec 01 20:39:14 iris systemd[1]: Started Simple Desktop Display Manager.
Dec 01 20:39:14 iris sddm[678]: Initializing...
Dec 01 20:39:14 iris sddm[678]: Starting...
Dec 01 20:39:14 iris sddm[678]: Logind interface found
Dec 01 20:39:14 iris sddm[678]: Adding new display on vt 1 ...
Dec 01 20:39:14 iris sddm[678]: Loading theme configuration from ""
Dec 01 20:39:14 iris sddm[678]: Display server starting...
Dec 01 20:39:14 iris sddm[678]: Adding cookie to "/var/run/sddm/{61e8f2cd-8fc7-4ae6-a1c4-09fa87863969}"
Dec 01 20:39:14 iris sddm[678]: Running: /usr/bin/X -nolisten tcp -auth /var/run/sddm/{61e8f2cd-8fc7-4ae6-a1c4-09fa87863969} -background none -noreset -displayfd 17 -seat seat0 vt1
Dec 01 20:39:15 iris sddm[678]: Failed to read display number from pipe
Dec 01 20:39:15 iris sddm[678]: Could not start Display server on vt 1
Dec 01 20:40:05 iris sddm[678]: Signal received: SIGTERM
Dec 01 20:40:05 iris systemd[1]: Stopping Simple Desktop Display Manager...
Dec 01 20:40:05 iris systemd[1]: sddm.service: Succeeded.
Dec 01 20:40:05 iris systemd[1]: Stopped Simple Desktop Display Manager.
Dec 01 20:40:05 iris systemd[1]: Started Simple Desktop Display Manager.
Dec 01 20:40:05 iris sddm[951]: Initializing...
Dec 01 20:40:05 iris sddm[951]: Starting...
Dec 01 20:40:05 iris sddm[951]: Logind interface found
Dec 01 20:40:05 iris sddm[951]: Adding new display on vt 1 ...
Dec 01 20:40:05 iris sddm[951]: Loading theme configuration from ""
Dec 01 20:40:05 iris sddm[951]: Display server starting...
Dec 01 20:40:05 iris sddm[951]: Adding cookie to "/var/run/sddm/{1ab473e4-d729-42fe-9e54-0ad95272646b}"
Dec 01 20:40:05 iris sddm[951]: Running: /usr/bin/X -nolisten tcp -auth /var/run/sddm/{1ab473e4-d729-42fe-9e54-0ad95272646b} -background none -noreset -displayfd 17 -seat seat0 vt1
Dec 01 20:40:07 iris sddm[951]: Setting default cursor
Dec 01 20:40:07 iris sddm[951]: Running display setup script  "/usr/share/sddm/scripts/Xsetup"
Dec 01 20:40:07 iris sddm[951]: Display server started.
Dec 01 20:40:07 iris sddm[951]: Reading from "/usr/share/xsessions/plasma.desktop"
Dec 01 20:40:07 iris sddm[951]: Reading from "/usr/share/xsessions/plasma.desktop"
Dec 01 20:40:07 iris sddm[951]: Session "/usr/share/xsessions/plasma.desktop" selected, command: "/usr/bin/startplasma-x11"
... yay!

I get a few more details in the Xorg log, but nothing that's helping me understand the problem:

[     9.345] (EE) Screen 0 deleted because of no matching config section.
[     9.345] (II) UnloadModule: "modesetting"
[     9.345] (EE) Device(s) detected, but none match those in the config file.
[     9.345] (EE) 
Fatal server error:
[     9.345] (EE) no screens found(EE) 
[     9.345] (EE) 

Here are the full Xorg logs when it fails and when it doesn't.

* Sad log: https://pastebin.com/ZarBe6iJ <-- EDIT: corrected link
* Happy log: https://pastebin.com/qFDtsvMv

Any ideas? Thanks!

Last edited by Rob_H (2020-12-02 12:50:24)

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 24,308

Re: SDDM fails on startup with: "Failed to read display number from pipe"

Try adding i915 at least to early KMS: https://wiki.archlinux.org/index.php/Ke … _KMS_start , if that doesn't help already add the relevant nvidia modules as well: https://wiki.archlinux.org/index.php/NV … de_setting

If neither helped post your xorg config, and your happy and sad log are the same files (... happy), maybe including the actual failing one might give some further pointers, but based on the overall description I'm fairly certain it's the usual race condition.

Rob_H

Member

Registered: 2012-06-19

Posts: 72

Re: SDDM fails on startup with: "Failed to read display number from pipe"

Try adding i915 at least to early KMS: https://wiki.archlinux.org/index.php/Ke … _KMS_start , if that doesn't help already add the relevant nvidia modules as well: https://wiki.archlinux.org/index.php/NV … de_setting

Thanks, I will give that a try and report back.

If neither helped post your xorg config, and your happy and sad log are the same files (... happy), maybe including the actual failing one might give some further pointers, but based on the overall description I'm fairly certain it's the usual race condition.

Bah! Sorry, I got my pastes mixed up. I have edited the URL in the original post to point to the correct sad log.

Rob_H

Member

Registered: 2012-06-19

Posts: 72

Re: SDDM fails on startup with: "Failed to read display number from pipe"

Yes, adding i915 to MODULES in mkinitcpio.conf and then regenerating fixed it. Thank you!