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Chad's Development Tools

Summary
=======
These are little scripts that I use to for setting up my environment, building
projects, etc.

There are no stability guarantees here, other than "it works for me".


How to Install
==============
These scripts don't require installation. You can execute them directly from
the git checkout. For example, suppose you have cloned Mesa to ~/src/mesa and
these dev-tools to ~/src/chadv-dev-tools. Then you can configure Mesa with the
mesa-configure script as follows:

    $ cd ~/src/mesa
    $ ~/src/chadv-dev-tools/mesa-configure

However, these scripts also work correctly if executed from an installed
location. If you prefer to install them, then:

    1. Configure:

        $ cp config.mk.example config.mk
        $ ed config.mk

    2. Build and install:

        $ make
        $ make install


USE flags
=========
The "USE" environment variable modifies the behavior of the configure scripts
(such as 'mesa-configure'). Its value is a space-separated list of flags,
called "USE flags". This project borrowed the concept of USE flags from
Gentoo's Portage buildsystem.

Some USE flags are common to all configure scripts, such as the "debug" flag.
Some USE flags are specific to a particular set of projects, such as the "dri3"
USE flag which affects only the configuration of projects that use DRI3.

Each flag listed in the USE environment variable, if prefixed with "-",
disables a particular project feature. Each flag, if prefixed with "+" or if it
has no prefix, enables a particular project feature.

Each project has a default list of USE flags defined in the Python variable
lib/chadv_dev_tools/${project}.py:Pkg.USE. The list of USE flags defined in
the environment modifies on the project's default list. The script
${project}-show-use-flags prints the USE flags that script ${project}-configure
would use, as currently defined by the environment and the project's defaults.

Example: Mesa
-------------
Suppose the default USE flags defined by lib/chadv_dev_tools/mesa.py is:

    USE="gbm dri3 x11 wayland surfaceless"

Verify the defaults:

    $ mesa-show-use-flags
    +gbm +dri3 +x11 +wayland +surfaceless

Try temporarily disabling the 'dri3' USE flag:

    $ USE="-dri3" mesa-show-use-flags
    +gbm -dri3 +x11 +wayland +surfaceless
    $ USE="" mesa-show-use-flags
    +gbm +dri3 +x11 +wayland +surfaceless

To disable DRI3 support when configuring Mesa, run:

    $ USE="-dri3" mesa-configure

To configure Mesa in debug mode (as opposed to release mode), and additionally
disable support for DRI3 and EGL's surfaceless platform, run:

    $ USE="debug -dri3,-surfaceless" mesa-configure

For Mesa, USE="debug" instructs mesa-configure to pass the following options to
Mesa's Autoconf configure script:

    * CFLAGS="-g3 -O0"
    * CXXFLAGS="-g3 -O0"
    * --enable-debug, which is a non-standard Autoconf option specific to Mesa



Installing graphics libraries to a non-standard location
========================================================

- If you have not already done so, place the devel scripts (mesa-configure,
  libdrm-configure, etc) onto your environment's PATH.

  If you wish to run the scripts directly from a git checkout, then:

        $ export PATH="/path/to/chadv-dev-tools/bin:$PATH"

  If you installed the scripts with `make install`, then these instructions
  assume that your PATH is already setup correctly.

  Before proceeding, confirm that the scripts lie on your PATH.

        $ which mesa-configure
        /some/path/to/mesa-configure
        $ which prefix-env
        /some/path/to/prefix-env

- Check which Mesa version you're running. Later, after installing a custom
  Mesa, we'll verify the installation by confirming that the active Mesa
  version has changed.

        $ glxinfo > /tmp/glxinfo-old.txt
        $ grep Mesa /tmp/glxinfo-old.txt

- Choose some prefix directory into which you will install the graphics
  libraries. These instructions use the directory /opt/my-prefix, but any
  directory will work.

- Before building any libraries, we must setup the shell's environment to use
  /opt/my-prefix. You could set all the needed environment variables manually.
  But setting them manually is prone to error because (1) it's easy to overlook the
  many variables that must be set and because (2) some variables, such as
  LD_LIBRARY_PATH, when set in the obvious way will trigger subtle error-laden
  easter eggs [1].

  First, inspect the changes that prefix-env will make to the shell's
  environment:

        $ prefix-env eval --prefix=/opt/my-prefix

  If all looks good, then import the changes into the environment:

        $ eval $(prefix-env eval --prefix=/opt/my-prefix)

- Next, we configure, build, and install libdrm.

  Change directories into your libdrm repository, and configure libdrm with the
  libdrm-configure script.

        $ PREFIX=/opt/my-prefix libdrm-configure

  Or, if you want a debug build:

        $ USE="debug" PREFIX=/opt/my-prefix libdrm-configure

  Each ${project}-configure script respects the USE and PREFIX environment
  variables. The USE environment variable enables and disables configuration
  options. The PREFIX environment variable defines the project's installation
  location.

  Then build and install.

        $ make
        $ make install

- Next, we configure, build, and install Mesa.

  Change directories into your mesa repository, and configure mesa with the
  mesa-configure script:

        $ PREFIX=/opt/my-prefix mesa-configure

  Or, if you want a debug build:

        $ USE="debug" PREFIX=/opt/my-prefix mesa-configure

- Confirm that the environment's Mesa version matches the version you
  installed. It should differ from the Mesa version we checked earlier.

        $ glxinfo > /tmp/glxinfo-new.txt
        $ grep Mesa /tmp/glxinfo-new.txt


Footnotes
==========
[1]: When LD_LIBRARY_PATH is empty, then setting it with
    `LD_LIBRARY_PATH=/some/path:${LD_LIBRARY_PATH}` can lead to unexpected
    surprises.  When loading an executable, `ld` interprets the trailing, empty
    path as the executable's working directory.