source: README.BLFS@ 7e51281

$Id$

1. INTRODUCTION::

     If you want to add blfs-tool support into an xLFS base system build,
  read the "BLFS_TOOL SUPPORT" section found in the README and be sure
  to follow the after-booting installation intructions.

     To automate package builds from the BLFS book instructions is a huge
  task. Some of the issues are: the BLFS book isn't linear; some package
  pages use a custom layout; there are circular dependencies; several
  packages can be installed on a non-default prefix; build commands can
  change based on what dependencies will be used, etc.

     That being said, the goal of the blfs-tool is to help you solve package
  dependencies, create build scripts and a Makefile. Few of the auto-generated
  build scripts and Makefile will work "as is", thus, as a general rule,
  you will need to review and edit the scripts while reading the book.


2. PREREQUISITES::

     To use this tool you MUST:

     - have experience building BLFS packages
     - know how to edit and write shell scripts
     - know how a Makefile works
     - be able to trace build failures and to find what is causing it
       (user error, package bug, BLFS command bug, or jhalfs code bug)

     If you do not have the above skills, please don't use this tool.


3. USAGE::

     Due the complexity of the BLFS book, the scripts and Makefile generation
  is done in several steps:

  3.1  INSTALLED PACKAGES TRACKING SYSTEM::

       This tool includes a very simple tracking system to log which packages
    have been installed using the tool. It is used to skip installed packages
    from target selection menu and to test if an installed package has been
    updated in the BLFS book. Do not rely on this feature as a package
    management tool.

       The tracking system itself is an XML file: instpkg.xml. It is
    initialized when make is first run in blfs_root. It resides in a directory
    which is created when needed during the process of building custom tools
    or blfs tools, after xLFS. You can specify that directory location in
    the blfs tools submenu of jhalfs. You may need to update permissions
    and/or ownership of this directory before using the blfs tool.

       The default location of the tracking directory is /var/lib/jhalfs/BLFS

  3.2  BLFS_TOOL INSTALLATION::

       The tools are installed just after the building of xLFS, if the
    appropriate options have been selected in the building menu, as per
    jhalfs README. If you forgot to select the options and xLFS has been
    built, it is possible to go back to selecting the appropriate
    BLFS tools options in the jhalfs menu, then tick `Run makefile'
    and not `Rebuild files'. You obtain a /blfs_root directory in the
    root directory of the new xLFS system, which contains the followings:

    blfs-xml/*         SVN tree of the selected BLFS book version
    lib/*              functions libraries 
    menu/*             lxdialog and menuconfig source code
    xsl/*              XSL stylesheets used at several stages of the process
    README.BLFS        this file
    TODO               developers notes (well, not often updated)
    gen_pkg_book.sh    resolves dependencies and generates linear BLFS books
                       and build scripts
    gen-makefile.sh    generates the target Makefile
    progress_bar.sh    the target Makefile progress bar
    gen-special.sh     Helper script for generating the package database
    Makefile           Used by make to update the package database from the SVN
                       tree, then launch the menuconfig interface, and run
                       gen_pkg_book.sh based on configuration settings
    packages.xml       auto-generated packages database
    packdesc.dtd       a simple DTD describing the format of the package
                       database
    envars.conf        envars needed when running the target build scripts

       From now on, all the work must be done from inside the installation
    root directory.

       You may move that directory to the $HOME of a non root user, or build
    as root from that directory.

  3.3  UPDATING BOOK SOURCES::

       If you are using the development book version and you want to update
    installed packages to the latest version found in that book, you need to
    update the XML sources and packages database.

       To do that run "make update". It may happen that the subversion
    version of your building host is older than the version you just
    built. This may generate weird errors like "'.' omitted". The easiest
    thing to do in that case, is to completely remove the blfs-xml directory
    and run "make update".

       On the next configuration run, packages already installed but listed
    with a new version in the book will be available for target selection
    and used to solve dependencies.

  3.4  CONFIGURING AND PARSING THE BOOK::

       The next step is to create a book and build scripts in dependency
    build order for one or several packages.

       Run <make> to launch the configuration interface. The main menu contains
    two blocks: individual package selection, and build options.

       In the build options section, the dependencies level and default packages
    used to solve alternatives are set (currently, only for the mTA). You can
    also select whether the build will be made as a normal user or as root.
    Those settings are saved to be reused in future configuration runs.

       When you are done with the menu, a few checks occur, and the book is
    generated. When circular dependencies are found, a 3 line message is
    printed:
           A is a dependency of B
           C is a dependency of A
           A is a dependency of C
    and a question:
           Do you want to build A first?
    This means that the system has found the dependency chain: B->A->C->A.
    You have therefore to choose whether A is built before C, or
    C before A: the system cannot make that choice (well, maybe in a few
    year, with an AI system able to understand the book). if you answer no,
    C is built first. If you answer yes, C is put in place of A as a dependency
    of B, then the tree dependency restarts from there, that is with the
    layout B->C->... You may then hit the case B->C->A->C, for which you
    should answer no, unless you want to enter an infinite (human driven) loop.

       You end up with a book.xml file which contains the linearized book,
    and a rendered HTML, in the directory book-html, which you can browse with
    "lynx book-html/index.html" (or with any other browser).

       Furthermore, there is a directory "scripts", which contains the generated
    scriptlets.

       There is also another directory, "dependencies" that contains files
    generated while resolving dependencies.

  3.5  EDITING BUILD SCRIPTS

       Now it is time to review the generated book and scripts, making any
    changes to the scripts necessary to fix generation bugs or to suit your
    needs.

       Scripts for additional packages (i.e., for non-BLFS packages) can be
    easily inserted. For example, if you want to install the external dependency
    "bar" before "foo" package and the "foo" script is named "064-z-foo", you
    just need to create a "064-y-bar" build script.

      Remember, the package tracking system isn't a package management tool
    and knows nothing about packages not in the BLFS book.

      Also, review and edit envars.conf. This file is used to set global envars
    needed by the build scripts.

  3.6  CREATING THE MAKEFILE

       When the build scripts are ready to be run, the Makefile can be
    created. Create an empty directory (for example "mkdir work") and cd
    to that directory. Then run ../gen-makefile.sh

    Review the Makefile, and, if all looks sane, start the build by running
    "make".

4. GENERATED BUILD SCRIPTS ISSUES::

      In this section, known issues with the generated build scripts are
   discussed. They are due to build procedures and/or BLFS layout
   particularities that we can't handle. In several cases, editing the
   build scripts is mandatory.
   You may also need to insert some build scripts created by you to resolve
   unhandled dependencies and/or to remove some script installing the affected
   package by hand.

   4.1  BLFS BOOTSCRIPTS

      Normally, bootscript installation should work. On the other hand, the
   book does not give instruction for running them, so you might have to
   manually insert /etc/init.d/<initscript> at some place during the build.

   4.2  PACKAGE CONFIGURATION

      For those packages that have a "Configuration" section, you should
   edit the build script to fit the needs of your system. Sometimes, the
   bash startup files are modified (see for example the instructions for
   llvm). You might have to insert something like "source /etc/bash_profile"
   at some point during the build.

   4.4  GCC, JDK, Sane, and KDE-multimedia, freetype2, MesaLib and others

        On the pages for those packages, the BLFS book actually has instructions
     to download and install two or more packages. You must edit the scripts to
     fix this.

        We will try to fix some of them, but this may not be possible.

   4.5  XORG7

        The generated scripts for Xorg7 packages have $SRC_ARCHIVE
     support for individual packages, but not for patches nor *.wget and *.md5
     files.

        If you have previously downloaded the patches, you must edit
     the scripts to use your local packages.

       The *.wget and *.md5 files should be downladed always from inside
     the scripts to be sure that the most current individual packages are
     used. Thus don't reuse previously existing ones.

       In the script for xorg7-font, be sure to move the fonts directories
     symlinks creation to after the "for ... done" loop.

   4.6  PATCHES

        By default, all required patches will be downloaded from the NET.

        If you have previously downloaded the patches, you must edit the
     scripts to use your local patches.

        Also, be sure that all scripts have the commands to download/apply the
     required patches. Due to book layout issues, some patches may be missing.

   4.7  ROOT COMMANDS

        If building as a normal user (the default setting), be sure that all
     commands that require root privileges are run using sudo. Also make sure
     necessary root privilege commands are visible in your PATH.

        Due to book layout issues, some sudo commands may be missing.

   4.8  OTHERS

        There may be other issues that we are not aware of. If you find
     any, please report it to <alfs-discuss@linuxfromscratch.org>.