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+# Notes on building Xenocara for OpenBSD X hackers
+
+This document presents some techniques that can be useful for people
+wanting to hack the xenocara tree. It assumes some basic knowledge of
+the OpenBSD build system, as described in the release(8) manual page.
+
+## About Xenocara
+
+Xenocara is the name chosen for OpenBSD's version of X. It's
+currently based on X.Org 7.7 and its dependencies. The goal of
+Xenocara is to provide a framework to host local modifications and to
+automate the build of the modular X.Org components, including 3rd
+party packages and some software maintained by OpenBSD developers.
+
+## Source tree
+
+The organisation of the xenocara directory follows the general
+organisation used in X.Org:
+
+- app: X applications and utilities
+- data: various data files (keyboard mappings and bitmaps)
+- doc: documentation
+- driver: input and video drivers
+- font: fonts
+- lib: libraries
+- proto: X protocol headers
+- util: utilities that don't fit anywhere else
+- xserver: the source for the X servers
+
+In addition Xenocara uses the following directories:
+
+- dist: contains some of the 3rd party sources, when keeping them separate
+  helps the build system (fontconfig, xcb and xkeyboard-config)
+- distrib: all binary distribution related tools and data
+- etc: some default config files
+- share: make(1) configuration for Xenocara
+
+At the top-level directory two files describe the individual
+components of Xenocara:
+
+- MODULES: lists all X.Org components (imported from the X.Org distribution
+  at http://xorg.freedesktop.org/archive/)
+- 3RDPARTY: lists all 3rd party software components provided in Xenocara,
+  either as dependencies of the X.Org software, or as complements
+  to it to provide a more useable default environment.
+
+## Compiling and installing
+
+Xenocara is made up of almost three hundred different independent
+packages that need to be built and installed in the right order,
+especially while bootstrapping (while /usr/X11R6 is still empty). The
+Xenocara Makefiles take care of that using the 'build' target.
+
+### Quick startup guide
+
+The following steps will build and install everything for the first time.
+
+    cd /usr/xenocara
+    doas make bootstrap
+    doas make obj
+    doas make build
+
+If you want to use another obj directory see below.
+
+### Requirements
+
+A freshly checked out xenocara tree is buildable without any external
+tool. Only the xenocara and the src (currently only the
+src/sys/dev/pci/pcidevs file) trees are needed.
+
+However if you start modifying things in the automake build
+system used by many packages, you will need to have the following
+GNU autotools packages installed:
+
+- automake 1.12 (devel/automake/1.12)
+- autoconf 2.71 (devel/autoconf/2.71)
+- metaauto (devel/metaauto)
+- libtool (devel/libtool)
+- gettext-tools (devel/gettext)
+
+If you have your source tree on an NFS partition, make sure the clocks
+of your server and client are properly synchronised. Any significant
+drift will cause various problems during builds.
+
+### Path
+
+To build Xenocara, you need to have /usr/X11R6/bin in your PATH.
+
+If you have installed the full Xenocara X sets on your system, you
+don't need to build all of Xenocara to patch one element. You can go
+to any module sub-directory and run 'make build' from there.
+
+#### Source directory
+
+The variable XSRCDIR can be set either in the environment or in
+/etc/mk.conf to point to the xenocara source tree, in case you keep it
+in a non-standard directory (the default is /usr/xenocara).
+
+#### Objdirs
+
+Xenocara requires objdirs. Just run 'make obj' as root at any level
+before 'make build' to make sure that the object directories are
+created.  XOBJDIR defines the obj directory that is used (defaults to
+/usr/xobj).  It should be created before running 'make obj'.
+
+## Regenerating configure scripts
+
+Whenever you touched an import file for GNU autotools (Makefile.am,
+configure.ac mostly), you need to rebuild the configure script and
+makefiles skeletons. For that use the following command in the
+directory where you edited the autotools source files:
+
+    make -f Makefile.bsd-wrapper autoreconf
+    doas make -f Makefile.bsd-wrapper build
+
+# Cleaning in packages managed by autotools
+
+One common problem when building xenocara is the case where the obj
+directory didn't exist (or the symbolic link pointed to a non-existent
+directory) when the source was first built. After fixing this problem,
+'configure' will refuse to work in the obj dir, because the source
+is already configured.
+
+To recover from this in one package:
+
+    rm -f obj
+    make -f Makefile.bsd-wrapper cleandir
+    mkdir XOBJDIR
+    make -f Makefile.bsd-wrapper obj
+    doas make -f Makefile.bsd-wrapper build
+
+or from the root of the xenocara tree:
+
+    find . -type l -name obj | xargs rm -f
+    make cleandir
+    mkdir XOBJDIR
+    make obj
+    doas make build
+
+for more desperate cases, remove all files from XSRCDIR not in CVS:
+
+    cd XSRCDIR
+    cvs -q update -PAd -I - | awk '$1=="?" {print $2}' | xargs rm -f
+
+# Updating XCB to a new release
+
+libxcb uses C source files that are generated from the XML protocol
+specification using xcbgen, written in Python. On OpenBSD those files
+cannot be generated during a normal 'make build' since Python is not
+in the base system. So the generated version are checked in CVS
+(in lib/libxcb/src/). Here is the receipt to update them when updating
+to a new release of XCB:
+
+1. Update proto/xcb-proto.
+2. Update the x11/py-xcbgen port to the same version and install the
+   python3 package.
+3. Update dist/libxcb.
+4. Check lib/libxcb/src/Makefile if new files need to be generated.
+5. Run `make` in lib/xcb/src to generate the files for the new version.
+6. Check lib/libxcb/ for other files needing updates.
+7. Commit the result.
+
+## How to build something with debug information?
+
+You can use `env CFLAGS=-g make -f Makefile.bsd-wrapper build` to
+build any module with debugging information, but you'll need to remove
+`XOBJDIR/xorg-config.cache.${MACHINE}` before doing that because
+autoconf caches the value of CFLAGS in its cache.
+
+##  How to get a core file out of the X server?
+
+Several things are needed:
+
+1. set kern.nosuidcoredump=3 in /etc/sysctl.conf
+2. start the X server as root, with the -keepPriv option. If you use
+   xenodm, you can add the option in /etc/X11/xenodm/Xservers. If you
+   want to use startx, you need to run it as root, like this:
+
+	`startx -- /usr/X11R6/bin/X -keepPriv`
+
+Now the X server should dump core when catching a fatal signal and the
+core dump should be in /var/crash/Xorg/<pid>.core.
+
+Alternatively, if the X server is using the modesetting(4) driver
+(it's the case with most recent AMD and Intel GPUs), it can be started
+as a regular user, without setting kern.nosuidcoredump=3, and the core
+dump will be in the current directory where startx was executed.
+
+See also http://xorg.freedesktop.org/wiki/Development/Documentation/ServerDebugging
+
+--
+$OpenBSD: README.md,v 1.1 2024/07/20 19:56:40 matthieu Exp $