docs: the desktop is Xorg on the framebuffer

xorg.md replaces wayland.md as Gate 3's plan: what is built, and the
ports left in order. 1.0.md's foundations row is brought up to date.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4

docs/plan/xorg.md

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+# Xorg
+
+The desktop is X11, on the framebuffer. This replaces [wayland.md](wayland.md)
+as the plan for Gate 3 of [1.0.md](1.0.md); Wayland stays on file and is not
+being worked on.
+
+## Why X and not Wayland
+
+Every Wayland compositor worth running -- labwc, and everything else built on
+wlroots -- needs DRM/KMS, libinput, udev and libseat. DRM/KMS is the largest of
+them by far: a kernel graphics subsystem, and in practice a great deal taken
+from Linux. Xorg runs on a plain framebuffer through its `fbdev` driver and
+reads input through `evdev`, both of which are interfaces SchOS already has.
+It is the shorter road to a desktop by a long way, and it brings the window
+managers with it: twm first, then Window Maker.
+
+DRM/KMS is not planned. libinput, udev and libseat are worth having for their
+own sake and may come later; Xorg does not need them.
+
+## What is built
+
+- **The kernel calls** (`b1323e1`, checked by `cmd/xready`): evdev's queries,
+  fbdev's mode-set to the current mode, `KDSETMODE`, `KDSKBMODE`, the
+  `VT_PROCESS` switch handshake, and `/sys/bus/pci/devices/*/{boot_vga,
+  enable,graphics/fb0}` for libpciaccess.
+- **Dynamic linking and `dlopen`** (`4330576`): Xorg loads its drivers as
+  modules.
+- **`<linux/*.h>`** in the build sysroot, as `ports/linux-headers`.
+
+## What is left, in order
+
+1. **The X client libraries.** xorgproto, xtrans, libXau, libXdmcp,
+   xcb-proto, libxcb, libX11, libXext, libXrender, libXfixes, libxkbfile,
+   libfontenc, libXfont2, freetype, zlib, pixman, libpciaccess.
+2. **Keyboard and fonts.** xkbcomp and xkeyboard-config, the data X compiles
+   keymaps from; a misc-fixed font.
+3. **The server.** xorg-server built with meson, GLX, glamor and DRI off;
+   xf86-video-fbdev; xf86-input-evdev with libevdev and mtdev.
+4. **The first picture.** `twm` and `xterm`, started by hand from a VT.
+5. **Window Maker**, and an `startx` that works.
+
+The kernel calls were written against what these programs are documented
+to do. Each step past it is expected to find a call that was not -- that is
+what running the real program is for.