smart-os/xfce4.md

# xfce4 组件介绍
* [ Gtk+ ] 这些组件 gtk 最庞大  
  libffi  
  libmount  
  glib  
  pixman  
  freetype  
  harfbuzz  
  fontconfig  
  cairo  
  fribidi  
  pango  
  gdkpixbuf  
  libeproxy  
  graphene  
  wayland-protocols  
  gettext( libintl )  
  gtk+  
* [ xfce ] 这些组件编译顺序也有要求  
  libwnck  
  xfce4-dev-tools  
  xlibxfce4util  
  xfconf  
  libxfce4ui  
  garcon  
  exo  
  xfce4-panel  
  thunar 
  xfce4-settings  
  xfce4-session  
  xfwm4  
  xfdesktop  
  thunar-volman  
  tumbler  
  xfce4-power-manager  
  xfce4-appfinder  

# Cairo 
cairo is a vector graphics library with cross-device output support  
cairo能够做各种复杂的点线图案绘制、填充、文字渲染、图像变换、剪切、层混合等等操作。但是他没有涉及到用户交互，如鼠标、touch、事件处理，交互窗口，这些统统没有，他只有专一的绘图。他有surface可以理解为画布，这个surface可以是基于内存（image surface，必选的surface）也可以基于某种backend（和操作系统或驱动接口对接），使用过程是创建一个surface，然后在surface里做各种绘图，最后使用Painting类的functions时图像就显示在了surface上。当然surface也是一块image，可以把image通过png（源码有对接libpng库）图像压缩输出png文件

# harfbuzz
HarfBuzz 是一个文本整形引擎。它主要支持OpenType，但也 支持Apple Advanced Typography。HarfBuzz 用于 Android、Chrome、ChromeOS、Firefox、GNOME、GTK+、KDE、LibreOffice、OpenJDK、PlayStation、Qt、XeTeX 等地方。


# xfce 运行黑屏怎么办
比如黑屏，我们由屏幕想到可能是 xfdesktop 这个应用负责渲屏，黑屏可能是 xfdesktop 未能正确运行，这个就需要我们手工调试跟踪了，通常情况下我们会这么做：
```shell
# 设置屏幕，这个是 xfce 默认的值 10
export DISPLAY=:10
# 执行这个，正常执行理论上就不会黑屏，不能执行，可能是依赖库路径不对，版本不对，配置不对，逐步根据提示解决问题
xfdesktop
```

# xrdp 远程访问 linux 桌面流程分析

1. xrdp 服务依赖 xrdp-sesman 服务
我们可以通过 grep 全局查找 xrdp-sesman，发现下面这句

```shell
./lib/systemd/system/xrdp.service:4:Requires=xrdp-sesman.service
```
因此 xrdp 启动时，肯定 xrdp-sesman 也相应启动，具体机制待研究(TODO)

2. 配置文件 /etc/xrdp/sesman.ini

```shell
[Globals]
ListenAddress=127.0.0.1
ListenPort=3350
```

3. 确认 xrdp 和 xrdp-sesman 服务

```shell
root@freeabc:/# netstat -anpt | grep xrdp
tcp6       0      0 :::3389                 :::*                    LISTEN      6288/xrdp           
tcp6       0      0 ::1:3350                :::*                    LISTEN      6259/xrdp-sesman
```
其中 xrdp 是 3389 对外提供服务, xrdp-sesman 是 3350 对 xrdp 提供服务，xrdp 把请求转给 xrdp-sesman (经过 tcpdump 抓包确认是)

```shell
root@freeabc:/# tcpdump -s 0 -i lo port 3350 -v -n
tcpdump: listening on lo, link-type EN10MB (Ethernet), capture size 262144 bytes
01:37:24.538435 IP6 (flowlabel 0xc281a, hlim 64, next-header TCP (6) payload length: 40) ::1.52600 > ::1.3350: Flags [S], cksum 0x0030 (incorrect -> 0x3f1d), seq 213438096, win 65476, options [mss 65476,sackOK,TS val 4262615841 ecr 0,nop,wscale 7], length 0
01:37:24.538457 IP6 (flowlabel 0xe10b3, hlim 64, next-header TCP (6) payload length: 40) ::1.3350 > ::1.52600: Flags [S.], cksum 0x0030 (incorrect -> 0xbea4), seq 3363004107, ack 213438097, win 65464, options [mss 65476,sackOK,TS val 4262615841 ecr 4262615841,nop,wscale 7], length 0
01:37:24.538472 IP6 (flowlabel 0xc281a, hlim 64, next-header TCP (6) payload length: 32) ::1.52600 > ::1.3350: Flags [.], cksum 0x0028 (incorrect -> 0xe53a), ack 1, win 512, options [nop,nop,TS val 4262615841 ecr 4262615841], length 0
01:37:25.149700 IP6 (flowlabel 0xc281a, hlim 64, next-header TCP (6) payload length: 109) ::1.52600 > ::1.3350: Flags [P.], cksum 0x0075 (incorrect -> 0x6a7f), seq 1:78, ack 1, win 512, options [nop,nop,TS val 4262616452 ecr 4262615841], length 77
01:37:25.149734 IP6 (flowlabel 0xe10b3, hlim 64, next-header TCP (6) payload length: 32) ::1.3350 > ::1.52600: Flags [.], cksum 0x0028 (incorrect -> 0xe028), ack 78, win 511, options [nop,nop,TS val 4262616452 ecr 4262616452], length 0
01:37:25.216918 IP6 (flowlabel 0xe10b3, hlim 64, next-header TCP (6) payload length: 62) ::1.3350 > ::1.52600: Flags [P.], cksum 0x0046 (incorrect -> 0xd13d), seq 1:31, ack 78, win 512, options [nop,nop,TS val 4262616519 ecr 4262616452], length 30
01:37:25.216969 IP6 (flowlabel 0xc281a, hlim 64, next-header TCP (6) payload length: 32) ::1.52600 > ::1.3350: Flags [.], cksum 0x0028 (incorrect -> 0xdf83), ack 31, win 512, options [nop,nop,TS val 4262616519 ecr 4262616519], length 0
01:37:25.254713 IP6 (flowlabel 0xe10b3, hlim 64, next-header TCP (6) payload length: 32) ::1.3350 > ::1.52600: Flags [F.], cksum 0x0028 (incorrect -> 0xdf5c), seq 31, ack 78, win 512, options [nop,nop,TS val 4262616557 ecr 4262616519], length 0
01:37:25.297973 IP6 (flowlabel 0xc281a, hlim 64, next-header TCP (6) payload length: 32) ::1.52600 > ::1.3350: Flags [.], cksum 0x0028 (incorrect -> 0xdf0b), ack 32, win 512, options [nop,nop,TS val 4262616600 ecr 4262616557], length 0
01:37:25.886713 IP6 (flowlabel 0xc281a, hlim 64, next-header TCP (6) payload length: 32) ::1.52600 > ::1.3350: Flags [F.], cksum 0x0028 (incorrect -> 0xdcbd), seq 78, ack 32, win 512, options [nop,nop,TS val 4262617189 ecr 4262616557], length 0
01:37:25.886737 IP6 (flowlabel 0xc429c, hlim 64, next-header TCP (6) payload length: 32) ::1.3350 > ::1.52600: Flags [.], cksum 0x0028 (incorrect -> 0xda45), ack 79, win 512, options [nop,nop,TS val 4262617189 ecr 4262617189], length 0
01:37:41.603074 IP6 (flowlabel 0x461f5, hlim 64, next-header TCP (6) payload length: 32) ::1.46136 > ::1.3350: Flags [F.], cksum 0x0028 (incorrect -> 0x23fc), seq 3577026672, ack 1112127163, win 512, options [nop,nop,TS val 4262632906 ecr 4262596309], length 0
01:37:41.603101 IP6 (flowlabel 0xeaed7, hlim 64, next-header TCP (6) payload length: 32) ::1.3350 > ::1.46136: Flags [.], cksum 0x0028 (incorrect -> 0x9506), ack 1, win 512, options [nop,nop,TS val 4262632906 ecr 4262632906], length 0
```

我们也可以利用 journalctl -xf 查看日志

```shell
Aug 18 01:45:02 freeabc xrdp[10507]: (10507)(139797313210176)[INFO ] Socket 12: AF_INET6 connection received from ::ffff:192.168.222.1 port 56030
Aug 18 01:45:02 freeabc xrdp[10507]: (10507)(139797313210176)[DEBUG] Closed socket 12 (AF_INET6 ::ffff:192.168.222.178 port 3389)
Aug 18 01:45:02 freeabc xrdp[10687]: (10687)(139797313210176)[DEBUG] Closed socket 11 (AF_INET6 :: port 3389)
Aug 18 01:45:03 freeabc xrdp[10687]: (10687)(139797313210176)[INFO ] Using default X.509 certificate: /etc/xrdp/cert.pem
Aug 18 01:45:03 freeabc xrdp[10687]: (10687)(139797313210176)[INFO ] Using default X.509 key file: /etc/xrdp/key.pem
Aug 18 01:45:03 freeabc xrdp[10687]: (10687)(139797313210176)[DEBUG] TLSv1.2 enabled
Aug 18 01:45:03 freeabc xrdp[10687]: (10687)(139797313210176)[DEBUG] TLSv1.1 enabled
Aug 18 01:45:03 freeabc xrdp[10687]: (10687)(139797313210176)[DEBUG] TLSv1 enabled
Aug 18 01:45:03 freeabc xrdp[10687]: (10687)(139797313210176)[DEBUG] Security layer: requested 11, selected 1
Aug 18 01:45:03 freeabc xrdp[10687]: (10687)(139797313210176)[INFO ] connected client computer name: DESKTOP-9PAUEP4
Aug 18 01:45:03 freeabc xrdp[10687]: (10687)(139797313210176)[INFO ] TLS connection established from ::ffff:192.168.222.1 port 56030: TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384
Aug 18 01:45:03 freeabc xrdp[10687]: (10687)(139797313210176)[DEBUG] xrdp_000029bf_wm_login_mode_event_00000001
Aug 18 01:45:03 freeabc xrdp[10687]: (10687)(139797313210176)[INFO ] Cannot find keymap file /etc/xrdp/km-00000804.ini
Aug 18 01:45:03 freeabc xrdp[10687]: (10687)(139797313210176)[INFO ] Cannot find keymap file /etc/xrdp/km-00000804.ini
Aug 18 01:45:03 freeabc xrdp[10687]: (10687)(139797313210176)[INFO ] Loading keymap file /etc/xrdp/km-00000409.ini
Aug 18 01:45:03 freeabc xrdp[10687]: (10687)(139797313210176)[WARN ] local keymap file for 0x00000804 found and doesn't match built in keymap, using local keymap file
Aug 18 01:45:03 freeabc xrdp[10687]: (10687)(139797313210176)[DEBUG] xrdp_wm_log_msg: connecting to sesman ip 127.0.0.1 port 3350
Aug 18 01:45:03 freeabc xrdp-sesman[10471]: (10471)(140145709626688)[INFO ] A connection received from ::1 port 36482
Aug 18 01:45:04 freeabc xrdp[10687]: (10687)(139797313210176)[INFO ] xrdp_wm_log_msg: sesman connect ok
Aug 18 01:45:04 freeabc xrdp[10687]: (10687)(139797313210176)[DEBUG] xrdp_wm_log_msg: sending login info to session manager, please wait...
Aug 18 01:45:04 freeabc xrdp[10687]: (10687)(139797313210176)[DEBUG] return value from xrdp_mm_connect 0
Aug 18 01:45:04 freeabc xrdp-sesman[10471]: (10471)(140145709626688)[INFO ] ++ created session (access granted): username root, ip ::ffff:192.168.222.1:56030 - socket: 12
Aug 18 01:45:04 freeabc xrdp-sesman[10471]: (10471)(140145709626688)[INFO ] starting Xorg session...
Aug 18 01:45:04 freeabc xrdp-sesman[10471]: (10471)(140145709626688)[DEBUG] Closed socket 9 (AF_INET6 :: port 5911)
Aug 18 01:45:04 freeabc xrdp-sesman[10471]: (10471)(140145709626688)[DEBUG] Closed socket 9 (AF_INET6 :: port 6011)
Aug 18 01:45:04 freeabc xrdp-sesman[10471]: (10471)(140145709626688)[DEBUG] Closed socket 9 (AF_INET6 :: port 6211)
Aug 18 01:45:04 freeabc xrdp-sesman[10688]: (10688)(140145709626688)[INFO ] calling auth_start_session from pid 10688
Aug 18 01:45:04 freeabc xrdp-sesman[10471]: (10471)(140145709626688)[DEBUG] Closed socket 8 (AF_INET6 ::1 port 3350)
Aug 18 01:45:04 freeabc xrdp[10687]: (10687)(139797313210176)[INFO ] xrdp_wm_log_msg: login successful for display 11
Aug 18 01:45:04 freeabc xrdp-sesman[10688]: pam_unix(xrdp-sesman:session): session opened for user root by (uid=0)
Aug 18 01:45:04 freeabc systemd-logind[1076]: New session c15 of user root.
-- Subject: A new session c15 has been created for user root
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
-- Documentation: https://www.freedesktop.org/wiki/Software/systemd/multiseat
-- 
-- A new session with the ID c15 has been created for the user root.
-- 
-- The leading process of the session is 10688.
Aug 18 01:45:04 freeabc systemd[1]: Started Session c15 of user root.
-- Subject: Unit session-c15.scope has finished start-up
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
-- 
-- Unit session-c15.scope has finished starting up.
-- 
-- The start-up result is RESULT.
Aug 18 01:45:04 freeabc xrdp-sesman[10688]: (10688)(140145709626688)[DEBUG] Closed socket 7 (AF_INET6 ::1 port 3350)
Aug 18 01:45:04 freeabc xrdp[10687]: (10687)(139797313210176)[DEBUG] xrdp_wm_log_msg: started connecting
Aug 18 01:45:04 freeabc xrdp-sesman[10688]: (10688)(140145709626688)[DEBUG] Closed socket 8 (AF_INET6 ::1 port 3350)
Aug 18 01:45:04 freeabc xrdp-sesman[10690]: (10690)(140145709626688)[INFO ] /usr/lib/xorg/Xorg :11 -auth .Xauthority -config xrdp/xorg.conf -noreset -nolisten tcp -logfile .xorgxrdp.%s.log
Aug 18 01:45:04 freeabc xrdp-sesman[10688]: (10688)(140145709626688)[CORE ] waiting for window manager (pid 10689) to exit
Aug 18 01:45:04 freeabc systemd[1487]: Started GnuPG cryptographic agent and passphrase cache.
-- Subject: Unit UNIT has finished start-up
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
--
-- Unit UNIT has finished starting up.
--
-- The start-up result is RESULT.
Aug 18 01:45:04 freeabc gpg-agent[10760]: gpg-agent (GnuPG) 2.2.4 starting in supervised mode.
Aug 18 01:45:04 freeabc gpg-agent[10760]: using fd 3 for ssh socket (/run/user/0/gnupg/S.gpg-agent.ssh)
Aug 18 01:45:04 freeabc gpg-agent[10760]: using fd 4 for extra socket (/run/user/0/gnupg/S.gpg-agent.extra)
Aug 18 01:45:04 freeabc gpg-agent[10760]: using fd 5 for std socket (/run/user/0/gnupg/S.gpg-agent)
Aug 18 01:45:04 freeabc gpg-agent[10760]: using fd 6 for browser socket (/run/user/0/gnupg/S.gpg-agent.browser)
Aug 18 01:45:04 freeabc gpg-agent[10760]: listening on: std=5 extra=4 browser=6 ssh=3
Aug 18 01:45:04 freeabc kernel: xfce4-session[10742]: segfault at 2c ip 0000556e4a4fe8c6 sp 00007ffedc54cd30 error 4 in xfce4-session[556e4a4d2000+45000]
Aug 18 01:45:04 freeabc xrdp[10687]: (10687)(139797313210176)[INFO ] lib_mod_log_peer: xrdp_pid=10687 connected to X11rdp_pid=10690 X11rdp_uid=0 X11rdp_gid=0 client_ip=::ffff:192.168.222.1 client_port=56030
Aug 18 01:45:04 freeabc xrdp[10687]: (10687)(139797313210176)[DEBUG] xrdp_wm_log_msg: connected ok
Aug 18 01:45:04 freeabc xrdp[10687]: (10687)(139797313210176)[DEBUG] xrdp_mm_connect_chansrv: chansrv connect successful
Aug 18 01:45:04 freeabc xrdp[10687]: (10687)(139797313210176)[DEBUG] Closed socket 20 (AF_INET6 ::1 port 36482)
Aug 18 01:45:04 freeabc xrdp[10687]: (10687)(139797313210176)[INFO ] The following channel is allowed: rdpdr (0)
Aug 18 01:45:04 freeabc xrdp[10687]: (10687)(139797313210176)[INFO ] The following channel is allowed: rdpsnd (1)
Aug 18 01:45:04 freeabc xrdp[10687]: (10687)(139797313210176)[INFO ] The following channel is allowed: cliprdr (2)
Aug 18 01:45:04 freeabc xrdp[10687]: (10687)(139797313210176)[INFO ] The following channel is allowed: drdynvc (3)
Aug 18 01:45:04 freeabc xrdp[10687]: (10687)(139797313210176)[DEBUG] The allow channel list now initialized for this session
Aug 18 01:45:04 freeabc xrdp-sesman[10688]: (10688)(140145709626688)[CORE ] window manager (pid 10689) did exit, cleaning up session
Aug 18 01:45:04 freeabc xrdp-sesman[10688]: (10688)(140145709626688)[INFO ] calling auth_stop_session and auth_end from pid 10688
Aug 18 01:45:04 freeabc xrdp-sesman[10688]: pam_unix(xrdp-sesman:session): session closed for user root
Aug 18 01:45:04 freeabc xrdp-sesman[10688]: (10688)(140145709626688)[DEBUG] cleanup_sockets:
Aug 18 01:45:04 freeabc xrdp[10687]: (10687)(139797313210176)[DEBUG] Closed socket 22 (AF_UNIX)
Aug 18 01:45:04 freeabc xrdp-sesman[10688]: (10688)(140145709626688)[DEBUG] cleanup_sockets: deleting /var/run/xrdp/sockdir/xrdp_chansrv_audio_out_socket_11
Aug 18 01:45:04 freeabc xrdp[10687]: (10687)(139797313210176)[DEBUG] Closed socket 12 (AF_INET6 ::ffff:192.168.222.178 port 3389)
Aug 18 01:45:04 freeabc xrdp-sesman[10688]: (10688)(140145709626688)[DEBUG] cleanup_sockets: deleting /var/run/xrdp/sockdir/xrdp_chansrv_audio_in_socket_11
Aug 18 01:45:04 freeabc xrdp[10687]: (10687)(139797313210176)[DEBUG] xrdp_mm_module_cleanup
Aug 18 01:45:04 freeabc xrdp[10687]: (10687)(139797313210176)[DEBUG] Closed socket 21 (AF_UNIX)
Aug 18 01:45:04 freeabc xrdp-sesman[10688]: (10688)(140145709626688)[DEBUG] cleanup_sockets: deleting /var/run/xrdp/sockdir/xrdpapi_11
Aug 18 01:45:04 freeabc xrdp-sesman[10471]: (10471)(140145709626688)[INFO ] ++ terminated session:  username root, display :11.0, session_pid 10688, ip ::ffff:192.168.222.1:56030 - socket: 12
Aug 18 01:45:14 freeabc systemd-logind[1076]: Removed session c15.
-- Subject: Session c15 has been terminated
```

这个日志可以看到更清楚的流程，具体日志见上
我们看到这个没启动起来是 xfce4-session[10742]: segfault at 2c ip 0000556e4a4fe8c6 sp 00007ffedc54cd30 error 4 in xfce4-session[556e4a4d2000+45000] 有段错误
这个错误，我们可以单独运行 xfce4-session 查看原因

```shell
xfwm4-Message: 02:00:03.303: Another Window Manager (Xfwm4) is already running on screen :10.0
xfwm4-Message: 02:00:03.303: To replace the current window manager, try "--replace"
(xfwm4:11384): xfwm4-WARNING **: 02:00:03.303: Could not find a screen to manage, exiting
```

我们看到是另外一个 Xfwn4 已经启动在 screen :10.0 了，可以运行 xfwm4 --replace 替换一下
对用户的授权，我们通过日志可以观察到是通过文件 ~/.Xauthority

5. xrdp-sesman 会根据 sesman.ini 调用 /etc/xrdp/startwm.sh，这个脚本最终会调用 /etc/X11/Xsession 这个脚本, Xsession 这个脚本大有文章

```shell
SYSSESSIONDIR=/etc/X11/Xsession.d
USERXSESSION=$HOME/.xsession  ---> 看到没有这就是我们经常看到的 echo "xfce4-session" > ~/.xsession 的原因，设置 Xsession 的环境变量
...
SESSIONFILES=$(run-parts --list $SYSSESSIONDIR)  ---> 最终会执行 /etc/X11/Xsession.d 下的脚本，我们所有的窗口会话实现，应该放到这个里面

if [ -n "$SESSIONFILES" ]; then
  set +e
  for SESSIONFILE in $SESSIONFILES; do
    echo $SESSIONFILES >> /root/my.log
    . $SESSIONFILE
  done
  set -e
fi

```

/etc/X11/Xsession.d/20dbus_xdg-runtime
/etc/X11/Xsession.d/20x11-common_process-args
/etc/X11/Xsession.d/30x11-common_xresources
/etc/X11/Xsession.d/35x11-common_xhost-local
/etc/X11/Xsession.d/40x11-common_xsessionrc
/etc/X11/Xsession.d/50x11-common_determine-startup
/etc/X11/Xsession.d/60x11-common_localhost
/etc/X11/Xsession.d/60x11-common_xdg_path
/etc/X11/Xsession.d/75dbus_dbus-launch
/etc/X11/Xsession.d/90gpg-agent
/etc/X11/Xsession.d/90qt-a11y
/etc/X11/Xsession.d/90x11-common_ssh-agent
/etc/X11/Xsession.d/95dbus_update-activation-env
/etc/X11/Xsession.d/99x11-common_start

参数 STARTUP 赋值
我们看到执行 /etc/X11/Xsession.d/50x11-common_determine-startup 时，会 STARTUP="$shell $STARTUPFILE" 其实就是 /bin/bash /root/.xsession , root就是 ~ 我们用 root 登录的。

参数 STARTUP 运行
我们跟踪执行 /etc/X11/Xsession.d/99x11-common_start/99x11-common_start 时，exec $STARTUP 这个其实就是执行 xfce4-session 了，至此 xfce4-session 启动完成

xfce4-session 会读取 下面的文件，并执行里面的命令
```shell
https://manpages.ubuntu.com/manpages/xenial/man1/xfce4-session.1.html
xfce4-session  reads its configuration from Xfconf.  xfce4-session stores its session data
into $XDG_CACHE_HOME/sessions/.
```

具体配置文件就是 /usr/local/etc/xdg/xfce4/xfconf/xfce-perchannel-xml/xfce4-session.xml
```xml
<?xml version="1.0" encoding="UTF-8"?>

<channel name="xfce4-session" version="1.0">
  <property name="general" type="empty">
    <property name="FailsafeSessionName" type="string" value="Failsafe"/>
    <property name="LockCommand" type="string" value=""/>
  </property>
  <property name="sessions" type="empty">
    <property name="Failsafe" type="empty">
      <property name="IsFailsafe" type="bool" value="true"/>
      <property name="Count" type="int" value="5"/>
      <property name="Client0_Command" type="array">
        <value type="string" value="xfwm4"/>
      </property>
      <property name="Client0_Priority" type="int" value="15"/>
      <property name="Client0_PerScreen" type="bool" value="false"/>
      <property name="Client1_Command" type="array">
        <value type="string" value="xfsettingsd"/>
      </property>
      <property name="Client1_Priority" type="int" value="20"/>
      <property name="Client1_PerScreen" type="bool" value="false"/>
      <property name="Client2_Command" type="array">
        <value type="string" value="xfce4-panel"/>
      </property>
      <property name="Client2_Priority" type="int" value="25"/>
      <property name="Client2_PerScreen" type="bool" value="false"/>
      <property name="Client3_Command" type="array">
        <value type="string" value="Thunar"/>
        <value type="string" value="--daemon"/>
      </property>
      <property name="Client3_Priority" type="int" value="30"/>
      <property name="Client3_PerScreen" type="bool" value="false"/>
      <property name="Client4_Command" type="array">
        <value type="string" value="xfdesktop"/>
      </property>
      <property name="Client4_Priority" type="int" value="35"/>
      <property name="Client4_PerScreen" type="bool" value="false"/>
    </property>
  </property>
</channel>
```

我们看到一个会话启动五个最基本的服务 xfwm4, xfsettingsd, xfce4-panel, Thunar, xfdesktop，如果启动失败，请依次排查这几个服务是否正常
如果只出状态栏和 Dock ，桌面出现黑屏，基本上是 xfdesktop 启动失败，可能依赖的库不满足，缺少什么库，这个需要具体问题具体分析了

# 常见问题解决方法
1. 解决 Fontconfig error: Cannot load default config file: No such file
cp /root/test/a/usr/local/etc/* /usr/local/etc/ -rf

2. 解决 Cannot read private key file /etc/xrdp/key.pem: Permission denied
adduser xrdp ssl-cert
reboot

3. 解决 libpango 库多版本的环境下，系统的低版本优先加载，导致 xfdesktop 不能正常启动的问题我们可以这么做
```shell
echo "LD_LIBRARY_PATH="/root/test/a/usr/lib:/root/test/a/usr/local/lib:/root/test/a/usr/lib/x86_64-linux-gnu" xfce4-session" > ~/.xsession
```
这样就可以优先加载我们编译的动态库了