lightdm.service waits for plymouth-quit-wait.service to release display resources

plymouth

安装plymouth-dbgsym

apt policy plymouth
plymouth:
  已安装：0.9.4.2-1+dde
  候选： 0.9.4.2-1+dde
  版本列表：
 *** 0.9.4.2-1+dde 500
        500 http://pools.uniontech.com/desktop-professional eagle/main amd64 Packages
        500 https://professional-security.chinauos.com eagle/1070/main amd64 Packages
        100 /usr/lib/dpkg-db/status

apt policy plymouth-dbgsym 
plymouth-dbgsym:
  已安装：(无)
  候选： 0.9.4.2-1+dde
  版本列表：
     0.9.4.2-1+dde 500
        500 http://pools.uniontech.com/desktop-professional eagle/main amd64 Packages
        500 https://professional-security.chinauos.com eagle/1070/main amd64 Packages

源码编译plymouth deb包

1	`apt source plymouth`

1	`cd plymouth-0.9.4.2/`

1	`sudo apt build-dep .`

1	`dpkg-buildpackage -b -uc -us -j16`

find . -name plymouth -type f
./debian/tmp/bin/plymouth
./debian/plymouth/etc/init.d/plymouth
./debian/plymouth/usr/share/lintian/overrides/plymouth
./debian/plymouth/usr/share/initramfs-tools/scripts/init-premount/plymouth
./debian/plymouth/usr/share/initramfs-tools/scripts/init-bottom/plymouth
./debian/plymouth/usr/share/initramfs-tools/scripts/panic/plymouth
./debian/plymouth/usr/share/initramfs-tools/hooks/plymouth
./debian/plymouth/bin/plymouth
./src/client/.libs/plymouth
./src/client/plymouth

1 2	`file ./src/client/plymouth ./src/client/plymouth: Bourne-Again shell script, ASCII text executable`

表明./src/client/plymouth不是要找的plymouth二进制elf文件。

1
2

file ./src/client/.libs/plymouth
./src/client/.libs/plymouth: ELF 64-bit LSB pie executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 3.2.0, BuildID[sha1]=56e45102a96d8f5a947ca80ed6267b917dee0e57, with debug_info, not stripped

表明./src/client/.libs/plymouth就是要找的plymouth二进制elf文件。

可以使用readelf命进一步确认：

readelf -S src/client/.libs/plymouth | grep -i debug
  [27] .debug_aranges    PROGBITS         0000000000000000  0000b252
  [28] .debug_info       PROGBITS         0000000000000000  0000b2c2
  [29] .debug_abbrev     PROGBITS         0000000000000000  000141e6
  [30] .debug_line       PROGBITS         0000000000000000  00014b34
  [31] .debug_str        PROGBITS         0000000000000000  00018587
  [32] .debug_loc        PROGBITS         0000000000000000  00019dfc
  [33] .debug_ranges     PROGBITS         0000000000000000  00021f45

plymouth-start.service

cat /lib/systemd/system/plymouth-start.service
[Unit]
Description=Show Plymouth Boot Screen
DefaultDependencies=no
Wants=systemd-ask-password-plymouth.path systemd-vconsole-setup.service
After=systemd-vconsole-setup.service systemd-udev-trigger.service systemd-udevd.service
Before=systemd-ask-password-plymouth.service
ConditionKernelCommandLine=!plymouth.enable=0
ConditionVirtualization=!container

[Service]
ExecStart=/sbin/plymouthd --mode=boot --pid-file=/run/plymouth/pid --attach-to-session
ExecStartPost=-/bin/plymouth show-splash
Type=forking
RemainAfterExit=yes
KillMode=none
SendSIGKILL=no

plymouthd作为daemon服务，plymouth作为前台进程。

grub

修改前的/etc/default/grub:

cat /etc/default/grub
# Generated by deepin-installer
GRUB_BACKGROUND="/boot/grub/themes/deepin-fallback/background.jpg"
GRUB_CMDLINE_LINUX_DEFAULT="video=efifb:nobgrt splash quiet "
GRUB_DEFAULT=0
GRUB_DISTRIBUTOR="`/usr/bin/lsb_release -d -s 2>/dev/null || echo UOS 20`"
GRUB_THEME="/boot/grub/themes/deepin-fallback/theme.txt"
GRUB_TIMEOUT=1
GRUB_GFXMODE=auto
DEEPIN_GFXMODE_DETECT=1

修改后的/etc/default/grub:

cat /etc/default/grub
# Generated by deepin-installer
GRUB_BACKGROUND="/boot/grub/themes/deepin-fallback/background.jpg"
GRUB_CMDLINE_LINUX_DEFAULT="video=efifb:nobgrt quiet plymouth:debug systemd.log_level=debug locales=zh_CN.UTF-8"
GRUB_DEFAULT=0
GRUB_DISTRIBUTOR="`/usr/bin/lsb_release -d -s 2>/dev/null || echo UOS 20`"
GRUB_THEME="/boot/grub/themes/deepin-fallback/theme.txt"
GRUB_TIMEOUT=1
GRUB_GFXMODE=auto
DEEPIN_GFXMODE_DETECT=1

grub中去掉splash参数后，plymouth相关的4个systemd服务依然会启动，只是不会展示log而已。

grub中增加参数plymouth:debug，将log打印到控制台，进入系统后可以直接查看var/log/plymouth-debug.log日志。

grub中增加参数增加systemd.log_level=debug，将systemd日志级别调整为debug。