Build X Server (Xorg) from Source
Motivation
Given that a difficulty to add a custom X11 device driver or module or extension for Xserver, I try to find out how an Xserver is built and its dependent drivers and modules and extensions are orgnized together by building it from source.
Build
Xorg 的源码库克隆下来后，checkout 到目标分支或 tag, 假设我们想编译 xorg-server-1.20.4 这个版本
1 | git checkout xorg-server-1.20.4 -b 1.20.4 // 将这个 tag 检出后命名为 1.20.4 分支 |
X Server 的源码库中除了 Xorg，还包含 modesetting_drv.so, xnest, xwin, xvfb 等，这些组件并不全都需要，如果全都编译，可能会有更多的依赖。
另外，Xorg 本身安装在 /usr/bin/ 目录, 其它相关 DDX 驱动安装在 /usr/lib/xorg/modules 目录，为了让编译好的 Xorg 和相关驱动安装后能够覆盖原来的，需要通过指定 meson 的 prefix 和 libdir 构建变量
1 | meson build -Dprefix=/usr -Dlibdir=lib -Dxnest=false -Dxwin=false -Dxvfb=false |
NOTES: 默认情况下，prefix=/usr/local, libdir=lib/x86_64-linux-gnu
构建配置完成后，进行编译
1 | ninja -C build |
编译完成后，使用 sudo 进行安装
1 | sudo ninja install -C build |
安装成功后，使用 systemd 重启 X Server 服务 （假设使用的窗口管理器是 lightdm)
1 | sudo systemctl restart lightdm |
It is easy to find what are built with find build -type f -perm /a+x -regex '.*[^0-9h]$'
./build/meson-private/sanitycheckc.exe ./build/test/tests ./build/test/simple-xinit ./build/hw/xnest/Xnest ./build/hw/vfb/Xvfb ./build/hw/xfree86/gtf ./build/hw/xfree86/vgahw/libvgahw.so ./build/hw/xfree86/libxorgserver.so ./build/hw/xfree86/fbdevhw/libfbdevhw.so ./build/hw/xfree86/drivers/modesetting/modesetting_drv.so ./build/hw/xfree86/dixmods/libglx.so ./build/hw/xfree86/dixmods/libwfb.so ./build/hw/xfree86/dixmods/libshadow.so ./build/hw/xfree86/shadowfb/libshadowfb.so ./build/hw/xfree86/cvt ./build/hw/xfree86/exa/libexa.so ./build/hw/xfree86/Xorg ./build/hw/xfree86/int10/libint10.so ./build/hw/xfree86/loader/xorg_symbol_test
where ./build/hw/xfree86/Xorg is newly built Xserver.
Replacement
Now that we have an Xorg out there, we can try it. I have an xrdp installed on my WSL as its desktop environment. We can replace xorgxrdp with this new one for testing. To do it, we need to modify xrdp’s init configuration file /etc/xrdp/sesman.ini
[Xorg] ; Specify the path of non-suid Xorg executable. It might differ depending ; on your distribution and version. The typical path is shown as follows: ; ; Fedora 26 or later : param=/usr/libexec/Xorg ; Debian 9 or later : param=/usr/lib/xorg/Xorg ; Ubuntu 16.04 or later : param=/usr/lib/xorg/Xorg ; Arch Linux : param=/usr/lib/xorg-server/Xorg ; CentOS 7 : param=/usr/bin/Xorg or param=Xorg ; ;param=/usr/lib/xorg/Xorg ; param=/home/luc/github/xserver/build/hw/xfree86/Xorg
But it failed on restart xrdp.service. We check the log and /etc/X11/xrdp/xorg.conf. It turns out some drivers related xrdp do not exist. It is xrdp that customizes Xorg.
1 | grep '(EE) Failed to' ~/.xorgxrdp.25.log |
[ 22862.100] (EE) Failed to load module "glx" (module does not exist, 0) [ 22862.100] (EE) Failed to load module "int10" (module does not exist, 0) [ 22862.100] (EE) Failed to load module "vbe" (module does not exist, 0) [ 22862.100] (EE) Failed to load module "glamoregl" (module does not exist, 0) [ 22862.100] (EE) Failed to load module "xorgxrdp" (module does not exist, 0) [ 22862.100] (EE) Failed to load module "xrdpdev" (module does not exist, 0) [ 22862.100] (EE) Failed to load module "xrdpmouse" (module does not exist, 0) [ 22862.100] (EE) Failed to load module "xrdpkeyb" (module does not exist, 0)
1 | grep -E '(Driver | Load)' /etc/X11/xrdp/xorg.conf |
Load "dbe"
Load "ddc"
Load "extmod"
Load "glx"
Load "int10"
Load "record"
Load "vbe"
Load "glamoregl"
Load "xorgxrdp"
Load "fb"
Driver "xrdpkeyb"
Driver "xrdpmouse"
Driver "xrdpdev"
Conclusion
Xserver/Xorg is built in a flexible and easy way. We can implement our own device-dependent functionality and add it to Xserver as its another driver or module.
Xserver 相关工具
xinit
1 | ➜ ~ dpkg --contents /var/cache/apt/archives/xinit_1.4.1-0ubuntu2_amd64.deb | awk '{print $NF}' | rg -v '/$' |