add plymouth

technology/linux/Plymouth.md

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+---
+obj: application
+arch-wiki: https://wiki.archlinux.org/title/Plymouth
+rev: 2024-12-20
+---
+
+# Plymouth
+Plymouth is a project from Fedora providing a flicker-free graphical boot process. It relies on kernel mode setting (KMS) to set the native resolution of the display as early as possible, then provides an eye-candy splash screen leading all the way up to the login manager. 
+
+## Setup
+By default, Plymouth logs the boot messages into `/var/log/boot.log`, and does not show the graphical splash screen.
+- If you want to see the splash screen, append `splash` to the kernel parameters.
+- If you want silent boot, append `quiet` too.
+- If you want to disable the logging, append `plymouth.boot-log=/dev/null`. Alternatively, add `plymouth.nolog` which also disables console redirection.
+
+To start Plymouth on early boot, you must configure your initramfs generator to create images including Plymouth.
+
+For mkinitcpio, add plymouth to the `HOOKS` array in `mkinitcpio.conf`:
+
+```sh
+# /etc/mkinitcpio.conf
+
+HOOKS=(... plymouth ...)
+```
+
+If you are using the `systemd` hook, it must be before `plymouth`.
+
+Furthermore make sure you place `plymouth` before the `crypt` hook if your system is encrypted with dm-crypt.
+
+## Configuration
+Plymouth can be configured in file `/etc/plymouth/plymouthd.conf`. You can see the default values in `/usr/share/plymouth/plymouthd.defaults`.
+
+### Changing the theme
+Plymouth comes with a selection of themes:
+- BGRT: A variation of Spinner that keeps the OEM logo if available (BGRT stands for Boot Graphics Resource Table)
+- Fade-in: "Simple theme that fades in and out with shimmering stars"
+- Glow: "Corporate theme with pie chart boot progress followed by a glowing emerging logo"
+- Script: "Script example plugin" (Despite the description seems to be a quite nice Arch logo theme)
+- Solar: "Space theme with violent flaring blue star"
+- Spinner: "Simple theme with a loading spinner"
+- Spinfinity: "Simple theme that shows a rotating infinity sign in the center of the screen"
+- Tribar: "Text mode theme with tricolor progress bar"
+- (Text: "Text mode theme with tricolor progress bar")
+- (Details: "Verbose fallback theme")
+
+The theme can be changed by editing the configuration file:
+
+```ini
+# /etc/plymouth/plymouthd.conf
+
+[Daemon]
+Theme=theme
+```
+
+or by running:
+
+```sh
+plymouth-set-default-theme -R theme
+```
+
+Every time a theme is changed, the initrd must be rebuilt. The `-R` option ensures that it is rebuilt (otherwise regenerate the initramfs manually).
+
+### Install new themes
+All currently installed themes can be listed by using this command:
+
+```sh
+plymouth-set-default-theme -l
+# or:
+ls /usr/share/plymouth/themes
+```
+
+### Show delay
+Plymouth has a configuration option to delay the splash screen:
+
+```ini
+# /etc/plymouth/plymouthd.conf
+
+[Daemon]
+ShowDelay=5
+```
+
+On systems that boot quickly, you may only see a flicker of your splash theme before your DM or login prompt is ready. You can set `ShowDelay` to an interval (in seconds) longer than your boot time to prevent this flicker and only show a blank screen. The default is 0 seconds, so you should not need to change this to a different value to see your splash earlier during boot.
+
+### HiDPI
+Edit the configuration file:
+
+```ini
+# /etc/plymouth/plymouthd.conf
+
+[Daemon]
+DeviceScale=an-integer-scaling-factor
+```
+
+and regenerate the initramfs. 
+
+## Misc
+### Show boot messages
+During boot you can switch to boot messages by pressing the `Esc` key. 
+
+### Disable with kernel parameters
+If you experience problems during boot, you can temporary disable Plymouth with the following kernel parameters:
+
+```
+plymouth.enable=0 disablehooks=plymouth
+```