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MahiroOS-jhalfs/README.BLFS
2017-03-20 14:15:28 +00:00

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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 instructions.
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. Not all 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 to 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 dependencies, right after xLFS. You can specify
that directory location in the blfs-tools sub-menu of jhalfs. You may
need to update permissions and/or ownership of this directory before
using the blfs tool (see README in jhalfs).
The default location of the tracking directory is /var/lib/jhalfs/BLFS.
NB : after the initial build, that directory is only used to contain
instpkg.xml, unless custom tools have been built. In the latter case,
it also contains empty files whose name are "$PKG-$VERSION" for each
versionned package built. The information about those packages is
included into instpkg.xml the next time the tool is run.
3.2 BLFS_TOOL INSTALLATION::
3.2.1 Normal install
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/constants.inc functions libraries
/func_dependencies for building the dependency tree
menu/* lxdialog and menuconfig source code
xsl/gen_pkg_list.xsl XSL stylesheet to generate the package database
/gen_config.xsl XSL stylesheet to generate the Config.in file
for use in the menuconfig system
/dependencies.xsl XSL stylesheet to generate the dependency list
of a package
/make_book.xsl XSL stylesheet to generate the linear book.xml
/scripts.xsl XSL stylesheet to generate the scriptlets from
book.xml
/bump.xsl XSL stylesheet to update the tracking file
README.BLFS this file
TODO developers notes (well, not updated often)
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
packdesc.dtd a simple DTD describing the format of the package
database and the tracking file.
envars.conf envars needed when running the target build scripts
3.2.2 Install to an already running LFS/BLFS system
If you forgot to install the tools when building xLFS, or want to try
the tools, you can select the BLFS book from the jhalfs menu. It will
run a script, which creates the above hierarchy in your home directory and
initialize the tracking file. You have first to make sure that the tracking
dir exists and is writable by the user. You may also populate it with
(empty) files whose names are of the form package-version, for installed
packages, so that they are included into the tracking file.
3.3.3 Working files
Several files are generated during the process:
packages.xml auto-generated packages database
Config.in input file for the menu driven choices
configuration file generated by the menuconfig process
dependencies/* files recording the dependency tree
book.xml the linearized book
book-html/* the linearized book rendered in html
scripts/* the scriptlets
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. This is not necessary if
you just built xLFS, and you can skip to step 3.4.
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". With recent versions of subversion, you can also
run "svn upgrade" from inside the blfs-xml directory.
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.
Note that you may select as many targets as you want, not just one
as in the previous version of this tool. But we suggest to not select
too many at a time to be able to sort issues!
When you are done with the menu, a few checks occur, and the dependency
chain is generated. Each dependency appears with its priority (required,
recommended, optional, or external), and it's level. There is a root level
1. The selected packages have level 2. The dependencies of selected packages
have level 3, the dependencies of the dependencies have level 4, and so on.
When circular dependencies are found, they appear with a priority of
"circular". This means that two (or more) dependency chains arrive at the
same package. The algorithm chooses the chain with the highest priority and
reorders dependencies to remove the other chain(s). This is not always the
solution an user would prefer, but we have found no way to do it better.
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 an unneeded
package (unneeded packages may be pulled in the dependency chain, if
they occur as an "or" with another package).
When there are circular dependencies (only one known in BLFS 8.0 for
recommended dependencies), you may need to move around scripts so that they
run in the order script-A script-B script-A. This involves copying script-A
to another name (using the xxx-a- fields), and possibly renaming the xxx-a-
fields of each involved script.
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/rc.d/<initscript> start" 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. The shipped 'envars.conf' contains a
line 'source /etc/profile', which ensures that the proper environment
variables are used.
4.3 PAGES WITH TWO OR MORE PACKAGES::
For example: sane, poppler, audacious, freetts, which, etc.
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. A common pitfall is that the variable PACKAGE may be used for
several tarballs. Be sure to save the PACKAGE variable to some other
name (for example PKG1, PKG2, etc) after each download. The unpacking
instructions may need to be repeated for each tarball in turn.
4.4 XORG7
The book has special page layouts for the Xorg7 packages. The tool
breaks those pages into individual pages for each packages in the linear
book. Also, the menu gives the choice to select each package individually.
To build the whole Xorg7 chapter, select twm. The (recommended)
dependency chain brings in the whole set of Xorg packages.
4.5 PATCHES
Please, make sure that all scripts have the commands to download/apply
the required patches. Due to book layout issues, some patches may be
missing (as of BLFS 8.0, all the patches seem to be downloaded).
4.6 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. Or use
the `Defaults secure_path=' in /etc/sudoers.
For commands necessitating root privileges, the generated scripts wrap
them with the construct:
sudo -E sh << ROOT_EOF
<commands to be executed as root with `$', ``', and `\' escaped>
ROOT_EOF
The -E switch ensures the whole environment is passed to the
commands to be run with root privileges. It is effective only if the
/etc/sudoers file contains `Defaults setenv', or SETENV in the user
attributes. If you think it is a security issue, you may forbid this
flag in /etc/sudoers, but then, you have to un-escape `$' for variables
coming from the environment in the instructions.
Although this construct is rather strong, it can fail in some corner
cases, so carefully review those instructions.
WARNING: One variable from the environment is not passed through the
-E switch, namely PATH. This is because "sudo" always reset the PATH to
the default "secure_path". If you need to have the same PATH as the user
"root" would have, you may want to add "source /etc/profile" at the
beginning of the commands to be executed as root.
Due to book layout issues, some sudo commands may be missing.
4.7 OTHERS
There may be other issues that we are not aware of. If you find
any, please report it to <alfs-discuss@linuxfromscratch.org>.