159 lines
6.4 KiB
Markdown
159 lines
6.4 KiB
Markdown
## What
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> kernel: `Linux 6.17.7-5-cachyos`
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>
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> nvidia-driver: `cachyos-v3/nvidia-open-dkms 580.105.08-3`
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>
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> sddm: `cachyos-v3/sddm 0.21.0-8`
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SDDM shows a blank screen (only with mouse cursor and tty cursor) after booting into graphical target, but starts normally after restarting the SDDM service.
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## Why
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SDDM starts before the NVIDIA driver is fully initialized, causing the greeter session to fail to display properly.
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<details>
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<summary>evidence</summary>
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- Logs after booting (many unrelated lines omitted):
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```log
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...
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systemd[1]: Started Simple Desktop Display Manager.
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kernel: NVRM: testIfDsmSubFunctionEnabled: GPS ACPI DSM called before _acpiDsmSupportedFuncCacheInit subfunction = 11.
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kernel: bridge: filtering via arp/ip/ip6tables is no longer available by default. Update your scripts to load br_netfilter if you need this.
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sddm[878]: Initializing...
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sddm[878]: Starting...
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sddm[878]: Logind interface found
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sddm[878]: Adding new display...
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sddm[878]: Loaded empty theme configuration
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sddm[878]: Xauthority path: "/run/sddm/xauth_yQfUmV"
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sddm[878]: Using VT 2
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sddm[878]: Display server starting...
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sddm[878]: Writing cookie to "/run/sddm/xauth_yQfUmV"
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sddm[878]: Running: /usr/bin/X -nolisten tcp -background none -seat seat0 vt2 -auth /run/sddm/xauth_yQfUmV -noreset -displayfd 16
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systemd[1]: Starting Authorization Manager...
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kernel: nvidia-modeset: WARNING: GPU:0: Unable to read EDID for display device DP-4
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kernel: nvidia-modeset: WARNING: GPU:0: Unable to read EDID for display device DP-4
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systemd[1]: Started Authorization Manager.
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kernel: [drm] Initialized nvidia-drm 0.0.0 for 0000:01:00.0 on minor 0
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systemd[1]: Started Power Profiles daemon.
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systemd[1]: Reached target Graphical Interface.
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kernel: nvidia 0000:01:00.0: [drm] Cannot find any crtc or sizes
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systemd[1]: Startup finished in 5.795s (firmware) + 7.387s (loader) + 1.169s (kernel) + 2.477s (initrd) + 3.421s (userspace) = 20.251s.
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systemd[1]: Starting Load/Save Screen Backlight Brightness of backlight:nvidia_0...
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systemd[1]: Finished Load/Save Screen Backlight Brightness of backlight:nvidia_0.
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sddm[878]: Setting default cursor
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sddm[878]: Running display setup script "/usr/share/sddm/scripts/Xsetup"
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sddm[878]: Display server started.
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sddm[878]: Socket server starting...
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sddm[878]: Socket server started.
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sddm[878]: Loading theme configuration from "/usr/share/sddm/themes/sugar-candy/theme.conf"
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sddm[878]: Greeter starting...
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sddm-helper[1006]: [PAM] Starting...
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sddm-helper[1006]: [PAM] Authenticating...
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sddm-helper[1006]: [PAM] returning.
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sddm-helper[1006]: pam_unix(sddm-greeter:session): session opened for user sddm(uid=950) by (uid=0)
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systemd[1]: Created slice User Slice of UID 950.
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systemd[1]: Starting User Runtime Directory /run/user/950...
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systemd-logind[773]: New session 'c1' of user 'sddm' with class 'greeter' and type 'x11'.
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systemd[1]: Finished User Runtime Directory /run/user/950.
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systemd[1]: Starting User Manager for UID 950...
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(systemd)[1015]: pam_warn(systemd-user:setcred): function=[pam_sm_setcred] flags=0x8002 service=[systemd-user] terminal=[] user=[sddm] ruser=[<unknown>] rhost=[<unknown>]
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(systemd)[1015]: pam_unix(systemd-user:session): session opened for user sddm(uid=950) by sddm(uid=0)
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systemd-logind[773]: New session '1' of user 'sddm' with class 'manager-early' and type 'unspecified'.
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systemd[1015]: Queued start job for default target Main User Target.
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systemd[1015]: Created slice User Application Slice.
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systemd[1015]: Startup finished in 139ms.
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systemd[1]: Started User Manager for UID 950.
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systemd[1]: Started Session c1 of User sddm.
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sddm-helper[1006]: Writing cookie to "/tmp/xauth_FfqCDd"
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sddm-helper[1006]: Starting X11 session: "" "/usr/bin/sddm-greeter --socket /tmp/sddm-:0-HQDlHk --theme /usr/share/sddm/themes/sugar-candy"
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sddm[878]: Greeter session started successfully
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...
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```
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Although the greeter session started successfully, it is not able to display anything due to `nvidia 0000:01:00.0: [drm] Cannot find any crtc or sizes`, resulting in a blank screen.
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- Logs after restarting sddm.service:
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```log
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...
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systemd[1]: Started Simple Desktop Display Manager.
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sudo[1123]: pam_unix(sudo:session): session closed for user root
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sddm[1150]: Initializing...
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sddm[1150]: Starting...
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sddm[1150]: Logind interface found
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sddm[1150]: Adding new display...
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sddm[1150]: Loaded empty theme configuration
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sddm[1150]: Xauthority path: "/run/sddm/xauth_XyLFOm"
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sddm[1150]: Using VT 1
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sddm[1150]: Display server starting...
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sddm[1150]: Writing cookie to "/run/sddm/xauth_XyLFOm"
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sddm[1150]: Running: /usr/bin/X -nolisten tcp -background none -seat seat0 vt1 -auth /run/sddm/xauth_XyLFOm -noreset -displayfd 16
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sddm[1150]: Setting default cursor
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sddm[1150]: Running display setup script "/usr/share/sddm/scripts/Xsetup"
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sddm[1150]: Display server started.
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sddm[1150]: Socket server starting...
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sddm[1150]: Socket server started.
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sddm[1150]: Loading theme configuration from "/usr/share/sddm/themes/sugar-candy/theme.conf"
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sddm[1150]: Greeter starting...
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sddm-helper[1217]: [PAM] Starting...
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sddm-helper[1217]: [PAM] Authenticating...
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sddm-helper[1217]: [PAM] returning.
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sddm-helper[1217]: pam_unix(sddm-greeter:session): session opened for user sddm(uid=950) by (uid=0)
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systemd-logind[773]: New session 'c2' of user 'sddm' with class 'greeter' and type 'x11'.
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systemd[1]: Started Session c2 of User sddm.
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sddm-helper[1217]: Writing cookie to "/tmp/xauth_Qghqzs"
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sddm-helper[1217]: Starting X11 session: "" "/usr/bin/sddm-greeter --socket /tmp/sddm-:0-YHEwdP --theme /usr/share/sddm/themes/sugar-candy"
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sddm[1150]: Greeter session started successfully
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...
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```
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</details>
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## How
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The key is to avoid timing race between NVIDIA initialization and SDDM start. There are multiple ways to achieve this, two for example:
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### Early KMS:
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As described in [Hyprland WIKI](https://wiki.hypr.land/Nvidia/#early-kms-modeset-and-fbdev), this ensures that the NVIDIA driver is loaded in the initramfs and is ready before SDDM starts (just randomly forgot to do this after reinstalling the system :D).
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1. enable `modset` in kernel parameters (e.g. in `/etc/default/grub`):
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```
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GRUB_CMDLINE_LINUX_DEFAULT="... nvidia-drm.modeset=1 ..."
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```
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and update grub:
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```sh
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sudo grub-mkconfig -o /boot/grub/grub.cfg
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```
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2. specify early loaded modules in `/etc/mkinitcpio.conf`:
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```
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MODULES=(... nvidia nvidia_modeset nvidia_uvm nvidia_drm ...)
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```
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and regenerate initramfs:
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```sh
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sudo mkinitcpio -P
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```
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3. reboot
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### Delay starting SDDM:
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`sudo systemctl edit sddm.service`
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```ini
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[Service]
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ExecStartPre=/bin/sleep 2
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```
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should also do the trick, but less elegant.
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