\input texinfo
@setfilename tlbuild.info

@set version 2014
@set month-year May 2014

@set mytitle Building @TeX{} Live (@value{version})
@settitle @value{mytitle}

@macro TL
@TeX{} Live
@end macro

@copying
This file documents the @TL{} build system and more.

Copyright @copyright{} 2013, 2014 Karl Berry & Peter Breitenlohner.

Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.

@ignore
Permission is granted to process this file through TeX and print the
results, provided the printed document carries a copying permission
notice identical to this one except for the removal of this paragraph
(this paragraph not being relevant to the printed manual).
@end ignore

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the
entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions,
except that this permission notice may be stated in a translation
approved by the @TeX{} Users Group.
@end copying

@c Put everything in one index (arbitrarily chosen to be the concept index).
@syncodeindex fn cp
@syncodeindex ky cp
@syncodeindex pg cp
@syncodeindex tp cp
@syncodeindex vr cp

@dircategory TeX
@direntry
* TL-build: (tlbuild).          TeX Live configuration and development.
@end direntry

@titlepage
@title @value{mytitle}
@subtitle @value{version} release
@subtitle @value{month-year}
@author Peter Breitenlohner
@author Karl Berry
@author @url{http://tug.org/tex-live}

@page
@vskip 0pt plus 1filll
@insertcopying
@end titlepage

@shortcontents
@contents

@ifnottex
@node Top
@top @value{mytitle}

For an overview of this manual, @pxref{Introduction}.

@menu
* Introduction::                About this manual.
* Overview of build system::    The @TL{} build system.
* Prerequisites::               Requirements for building @TL{}.
* Building::                    The overall build process.
* Installing::                  How and where installation happens (or not).
* Layout and infrastructure::   Autoconf macros, etc., in detail.
* Configure options::           List of all configure options.
* Cross compilation::           Building on host X for target Y.
* Coding conventions::          Conventions to follow.
* install-tl::                  The @TL{} installer.
* tlmgr::                       The native @TL{} package manager.
* Index::                       General index.
@end menu
@end ifnottex


@node Introduction
@chapter Introduction

@cindex introduction

This manual (dated @value{month-year}) corresponds to the @TL{}
@value{version} release.

This manual is aimed at system installers and programmers, and focuses
on how to configure, build, and develop the @TL{} (TL) sources.  The
sources can be acquired in a number of ways; see
@url{http://tug.org/texlive/svn}.

This manual does not duplicate the (primarily user-level) information
found in other TL documentation resources, such as:

@itemize
@item The @TL{} web pages: @url{http://tug.org/texlive}.

@item The web page with an overview of how to build the binaries which 
are distributed with @TL{}: @url{http://tug.org/texlive/build.html}.

@item The @TL{} user manual: @url{http://tug.org/texlive/doc.html}, or
run @code{texdoc texlive}.

@item Other @TeX{}-related Texinfo manuals (@pxref{,,,web2c, Web2c},
@ref{,,,kpathsea, Kpathsea}, etc.):
@url{http://tug.org/texinfohtml/}, or check the @samp{TeX} category in
the GNU Info system.

@item Package documentation:
@url{http://tug.org/texlive/Contents/live/doc.html}, or the
@file{doc.html} file at the top level of the installed TL.

@end itemize

As an exception, the full documentation for @code{install-tl} and
@code{tlmgr} is included here, just because it is convenient to do so.
The same text is available online (linked from
@url{http://tug.org/texlive/doc.html}, or by invoking the program with
@samp{--help} (or look at the end of the source file).


@c The first word of the chapter/section title here is used to
@c construct the README.* filenames, so choose well.  (Or hack the script.)

@node Overview of build system
@chapter Overview of build system

@cindex build system, design of

@cindex Autoconf
@cindex Automake
@cindex Libtool
@cindex tests, running
The @TL{} build system was redesigned in 2009, consistently using
Autoconf, Automake, and Libtool.  Thus@*@ @ @ @code{configure &&
make && make check && make install}@*or the basically-equivalent
top-level @code{Build} script suffice to build and install the TL
programs.  The @code{make check} clause performs various tests of the
generated programs---not strictly required but strongly recommended.
Running @code{configure --help} will display a comprehensive list of
all @code{configure} options.

The main components of the TL build system are:

@table @file
@item libs/@var{lib}
Generic libraries.

@item texk/@var{lib}
@TeX{}-specific libraries in subdirectories, notably
@var{lib}=@code{kpathsea}.  (The other one is @file{texk/ptexenc}.)

@item texk/@var{prog}
@TeX{}-specific programs (that use Kpathsea).

@item utils/@var{prog}
Other programs (that don't use Kpathsea).

@end table

@pindex kpse-pkgs.m4
The primary design goal of the build system is modularity.  Each
program and library module (or package) specifies its own requirements
and properties, such as required libraries, whether an installed
(system) version of a library can be used, @code{configure} options to
be seen at the top-level, and more.  An explicit list of all available
modules is kept in only one, central, place (@file{m4/kpse-pkgs.m4}).

A second, related goal is to configure and build each library before
configuring any other (program or library) module which uses that
library.  This allows checking for properties and features of a
library built as part of the TL tree in much the same way as for a
system version of that library.

All generic libraries and several programs are maintained
independently.  The corresponding modules use (most of) the
distributed source tree and document any modifications of that source.

All this is for the sake of simplifying both upgrading of modules
maintained independently and integrating new modules into the
TL build system.  (Not to say that either task is trivial.)


@node Prerequisites
@chapter Prerequisites

@cindex prerequisites for building
@cindex requirements for building

@cindex compilers, C and C++
Overall, building the @TL{} programs, when using all libraries from
the TL source tree, requires only C and C++ compilers and GNU
@code{make}.  (If @code{make} from your @code{PATH} is not GNU make,
you can set @code{MAKE} in the environment to whatever is necessary.)

@cindex GNU @code{make}, required
@cindex @code{gmake}, required
@cindex FreeType
Indeed, GNU @code{make} is required only because of some
third-party libraries, notably FreeType; all the TL-maintained
directories (and Automake/Autoconf output in general) should work with
any reasonable @code{make}.

However, a few programs in the tree have additional requirements:

@table @file
@item web2c
@cindex @code{perl}, required by @code{web2c}, etc.
requires @code{perl} for some tests run by @code{make check}.

@item xdvik
@itemx xpdfopen
@cindex X11, required by X clients
require X11 headers and libraries, often in ``development'' packages
that are not installed by default.

@item xetex
@cindex @code{fontconfig} library, required by @code{xetex}
requires @file{fontconfig} (again both headers and library).

@item xindy
@cindex @code{clisp}, required by @code{xindy}
@cindex @code{ffcall}, required by @code{xindy}
requires GNU @code{clisp} and in addition @code{perl}, @code{latex},
and @code{pdflatex} to build the rules and/or documentation.

@end table

@noindent Lacking the required tools, building these
programs must avoided, e.g.,@*
@code{configure --without-x --disable-xetex --disable-xindy}

Modifying source files induces more requirements, as one might expect:

@itemize
@item
Modification of any @code{.y} or @code{.l} source files requires
@file{bison} or @file{flex} to updatete the corresponding C sources.

@item
Modification of the sources for @code{.info} files requires
@code{makeinfo}.

@item
Modification of any part of the build system (M4 macros,
@file{configure.ac}, @file{Makefile.am}, or their fragments) requires
GNU M4, GNU Autoconf, GNU Automake, and GNU Libtool to update the
generated files.  @xref{Build system tools}.

@end itemize

If you haven't modified any source files, and infrastructure tools
such as @code{autoconf} or @code{makeinfo} are still being run, check
your timestamps---notably, @code{use-commit-times} must be set to
@code{yes} in your Subversion configuration (@pxref{Build system
tools}).  Barring buggy commits, no infrastructure tools are needed to
do a normal build.


@node Building
@chapter Building

@cindex building
@cindex overall build process

@pindex Build @r{script}
The top-level @file{Build} script is intended to simplify building the
binaries distributed with @TL{} itself---we call this the ``native''
TL build.  It configures and makes everything in a subdirectory of the
main build tree (default @file{Work/}), installs everything in an
other subdirectory (default @file{inst/}), and finally runs @code{make
check}.  The exact directory and command names can be specified via
environment variables and a few leading options.  All remaining
arguments (assignments or options) are passed to the @file{configure}
script.  Please take a look at the script itself for more information;
it is not complicated.

@cindex source directory building, not supported
@cindex build directory, required
An alternative, and the one we will mainly discuss here, is to run
@code{configure} and @code{make} oneself in a suitable empty
subdirectory.  Building in the source directory itself is not
supported (sorry).

@menu
* Build iteration::     What @code{configure} and @code{make} do.
* Build problems::      If the build fails.
* Build in parallel::   Simultaneous @code{make} processes.
* Build distribution::  Making a distribution tarball.
* Build one package::   Example of working on just one program.
@end menu


@node Build iteration
@section Build iteration

@cindex build iteration
@cindex iteration through sources, by @code{configure} and @code{make}

Running the top-level @file{configure} script configures the top level
and the subdirectories @file{libs}, @file{utils}, and @file{texk}.
Running @code{make} at the top-level first iterates over all
@TeX{}-specific libraries, and then runs @code{make} in
@file{libs}, @file{utils}, and @file{texk} to iterate over all generic
libraries, utility programs, and @TeX{}-specific programs.  These
iterations consist of two steps:

@enumerate
@item
For each library or program module not yet configured, run
@code{configure}, adding the configure option @code{--disable-build}
if the module need not be built, otherwise running @code{make all}.

@item
For each library or program module that must be built, run
@code{make} for the selected target(s): @code{default} or
@code{all} to (re-)build, @code{check} to run tests, @code{install},
etc.

@end enumerate

Running the top-level @code{make} a second time iterates again over
all the library and program modules, but finds (should find) nothing
to be done unless some source files have been modified.


@node Build problems
@section Build problems

@cindex build problems
@cindex problems with build
@cindex failure to build
@vindex --no-clean Build @r{option}
If configuring or building a module fails, you could either
(a)@tie{}find and fix the problem, or (b)@tie{}remove the subdirectory
for that module from the build tree, and rerun the top-level
@code{make} (or @file{Build} with @code{--no-clean} as its first
argument).


@node Build in parallel
@section Build in parallel

@cindex building in parallel
@cindex parallel build
@cindex cache for @code{configure}

@cindex dependencies, with several output files
@vindex -j make @r{option}
The TL build system carefully formulates dependencies as well as
@code{make} rules when a tool (such as @code{tangle}, @code{ctangle},
or @code{convert}) creates several output files.  This allows for
parallel builds (@code{make -j @var{n}} with @math{@var{n}>1} or even
@code{make -j}) that can considerably speed up the TL build.

@cindex cache file, for @code{configure}
@vindex -C configure @r{option}
Incidentally, a noticeable speed-up can also be (independently) gained
by using a configure cache file, i.e., with the option @code{-C}
(recommended).


@node Build distribution
@section Build distribution

@cindex building a distribution
@cindex distribution tarball, making

@cindex @code{dist} and @code{distcheck} targets for @code{make}
Running @code{make dist} at the top-level creates a tarball
@file{tex-live-@var{yyyy}-@var{mm}-@var{dd}.tar.xz} from the TL source
tree.  Running @code{make distcheck} also verifies that this tarball
suffices to build and install all of TL.

This is useful for checking consistency of the source tree and
Makefiles, but the result is not a complete or even usable @TeX{}
system, since all the support files are lacking; @pxref{Installing}.

@node Build one package
@section Build one package

@cindex build one package
@cindex one package, building

@vindex --disable-all-packages configure @r{option}
@cindex build on demand
To build one package, the basic idea is to use the @code{configure}
option @code{--disable-all-pkgs} (@pxref{@code{--disable-all-pkgs}}).
Then all program and library modules are configured but none are made.
However, the @file{Makefile}s still contain all build rules and
dependencies and can be invoked to build an individual program or
library and causes to first build any required libraries.

This ``build-on-demand'' procedure is used, e.g., in the @code{luatex}
repository to build Lua@TeX{}, essentially from a subset of the
complete @TL{} tree.  Similarly, when, e.g., building the original
e-@TeX{} has been disabled (as it is by default), one can run
@code{make etex} (or @code{make etex.exe}) in @file{texk/web2c/} to
build e-@TeX{} (although there is no comparably simple way to install
e-@TeX{}).

If you want to work on a single program within the TL sources, this is
the recommended way to do it.  Here is an example from start to
finish for working on @code{dvipdfmx}.

@example
mkdir mydir && cd mydir  # new working directory

# Get sources (@url{http://tug.org/texlive/svn})
rsync -a --delete --exclude=.svn --exclude=Work \
      tug.org::tldevsrc/Build/source/ .

# Create build directory:
mkdir Work && cd Work

# Do the configure:
../configure --disable-all-pkgs --enable-dvipdfm-x \
  -C CFLAGS=-g CXXFLAGS=-g >&outc

# Do the make:
make >&outm

# Test:
cd texk/dvipdfmx
make check
@end example

Then you modify source files in @file{mydir/texk/dvipdfm-x} and rerun
@code{make} in @file{mydir/Work/texk/dvipdfm-x} to rebuild.

The second line the @code{configure} are invocation shows examples of
extra things you likely want to specify if you intend to hack the
sources (and not just build binaries): the @code{-C} speeds up
@code{configure}, and the @code{CFLAGS} and @code{CXXFLAGS} are to
eliminate compiler optimization for debugging purposes.

Of course, one should actually look at the output and check that
things are working.  There are many @code{configure} options you can
tweak as desired; check the output from @code{configure --help}.

@cindex size of source tree
Finally, the above retrieves the entire TL source tree (some 300mb).
It is natural to ask if this is really necessary.  Strictly speaking,
the answer is no, but it is vastly more convenient to do so.  If you
cut down the source tree, you must also give additional
@code{configure} flags to individually disable using system versions
of libraries, or the intricacies of the dependencies (such as
@code{teckit} requiring @code{zlib}) will have undesired side effects.
For an example, see the @code{build-pdftex.sh} script in the
@code{pdftex} development sources (@url{http://pdftex.org}), which are
indeed a cut-down TL source tree.


@node Installing
@chapter Installing

@cindex installing
This section discusses the results of @code{make install} in the
source tree.

@cindex support files, separate from build
@pindex texlive.tlpdb@r{, @TL{} database}
@pindex install-tl@r{, @TL{} installer}
@pindex plain.tex@r{, not in source tree}
The main consideration is that @code{make install} is not enough to
make a usable @TeX{} installation.  Beyond the compiled binaries,
(thousands of) support files are needed; just as a first example
@file{plain.tex} is not in the source tree.

These support files are maintained completely independently and are
not present in the source tree.  The best basis for dealing with them
is the @TL{} (plain text) database in
@file{Master/tlpkg/texlive.tlpdb}, and/or the @TL{} installer,
@code{install-tl}.  More information is under @file{Master/tlpkg} and
at @url{http://tug.org/texlive/distro.html}.

@menu
* Installation directories::    The prefix, @code{bindir}, etc., directories.
* Linked scripts::              Scripts not maintained in the sources.
* Distro builds::               Configuring and building for OS distributions.
@end menu


@node Installation directories
@section Installation directories

@cindex installation directories
@cindex directories, for installation
@cindex paths, for installation

Running @code{make install} (or @code{make install-strip}) installs
executables in @code{@var{bindir}}, libraries in @code{@var{libdir}},
headers in @code{@var{includedir}}, general data (including ``linked
scripts'', @pxref{Linked scripts}) in
@code{@var{datarootdir}/texmf-dist}, man pages in @code{@var{mandir}},
and Info files in @code{@var{infodir}}.

The values of these directories are determined by @code{configure}
and can be specified explictly as options such as
@code{--prefix=@var{prefix}} or @code{--bindir=@var{bindir}};
otherwise, they are given by their usual Autoconf defaults:

@example
@var{prefix}                  /usr/local
@var{exec_prefix}             @var{prefix}
@var{bindir}                  @var{exec_prefix}/bin
@var{libdir}                  @var{exec_prefix}/lib
@var{includedir}              @var{prefix}/include
@var{datarootdir}             @var{prefix}/share    
@var{mandir}                  @var{datarootdir}/man
@var{infodir}                 @var{datarootdir}/info
@end example

@noindent @dots{} except possibly modified as follows:

@itemize @bullet
@item
If the option @code{--enable-multiplatform} is given,
@code{/@var{platform}} (i.e., the canonical platform name) is appended
to @code{@var{bindir}} and @code{@var{libdir}}.  This is implied for a
native TL build.

@item
@raggedright
In a native TL build, @code{@var{datarootdir}} is set to
@code{@var{prefix}}, @code{@var{infodir}} is set to
@code{@var{prefix}/texmf-dist/doc/info}, and @code{@var{mandir}} to
@code{@var{prefix}/texmf-dist/doc/man}, corresponding to the
directories used in the TL distribution.
@end raggedright

@end itemize

@noindent The top-level @file{configure} script displays all these
installation paths.

For the native TL build, the @code{Build} script leaves the binaries
in @file{./inst/bin/@var{std-platform-name}}.  The new binaries are
not directly usable from that location; they need to be copied to
@file{Master/bin/@var{tl-platform}}.  The other files and directories
that end up in @file{./inst/} are ignored.


@node Linked scripts
@section Linked scripts

@cindex linked scripts
@cindex scripts, linked and not maintained

@cindex symlinks, used for scripts
@cindex wrapper binary for scripts on Windows
@cindex Windows, invoking scripts on
Quite a few executables are architecture-independent shell, Perl, or
other interpreted scripts, rather than compiled binaries.  A few are
maintained as part of the TL source tree, but most are maintained
elsewhere with copies under @file{texk/texlive/linked_scripts}.

These so-called @dfn{linked scripts} are installed under
@code{@var{datarootdir}/texmf-dist/scripts}; for Unix-like systems a
symbolic link is made in @code{@var{bindir}}.  For example, a symlink
points from @code{@var{bindir}/ps2eps} to
@code{@var{datarootdir}/texmf-dist/scripts/ps2eps/ps2eps.pl}.  For
Windows, a standard wrapper binary (e.g.,
@code{@var{bindir}/ps2eps.exe}) serves the same purpose.  (The source
for the wrapper is in @file{texk/texlive/w32_wrapper}.)

One reason for this is to avoid having many copies of the same
script; a more important reason is that it guarantees the scripts will
stay in sync across the different supported operating systems.

@pindex asymptote
@pindex biber
@pindex xindy
@pindex xz
@pindex wget
Most important of all, we want the @code{@var{bindir}} resulting from
the build to be as close as possible to what is in the TL
distribution.  At present, there are a few exceptions---Asymptote,
Biber, Xindy---and each one creates considerable extra work.  We don't
want to add more.  (See @url{http://tug.org/texlive/build.html} for
information about building those exceptions, as well as the @code{xz}
and @code{wget} programs that are used in the TL infrastructure.)


@node Distro builds
@section Distro builds

@cindex distro, building for
@cindex operating system distribution, building for
@cindex system distribution, building for

@cindex GNU/Linux distro
@cindex BSD distro
Although they use the same code base, building for the native TL
distribution as shipped by the @TeX{} user groups is typically quite
different from a ``distro'' build needed by, e.g., a full GNU/Linux or
BSD operating system distribution.

@cindex shared libraries, using vs.@: avoiding
The native TL distribution uses shared libraries only when absolutely
necessary (@file{libc}, @file{libm}, X11 libraries, and
@file{libfontconfig}).  However, a distro typically wants to use as
many shared libraries as possible from elsewhere on the system,
including @TeX{}-specific libraries such as @file{libkpathsea} (even
though Kpathsea has never officially been released as a shared
library, but we digress).  In addition, the installation paths will,
in general, be completely different.

Here are the @code{configure} options that distro builds are likely to
find most relevant:

@table @code
@item --disable-native-texlive-build
This must be specified to avoid interference from the many tweaks we
do for the native TL build.

@item --with-banner-add=/@var{SomeDistro}
This isn't technically required, but is strongly recommended, so your
build and your distro can be distinguished from others.

@item --enable-shared
Build shared versions of the @TeX{}-specific libraries (uses
@code{libtool}).

@item --disable-static
Do not build the static versions of the @TeX{}-specific libraries.

@item --with-system-@var{lib}
Use system versions for as many libraries @var{lib} as possible.
@code{configure --help} will give you the list of possibilities.

@item --with-@var{lib}-includes=@var{dir}
@itemx --with-@var{lib}-libdir=@var{dir}
If needed, allows you to specify where the headers/code are for the
given library @var{lib}.

@item --prefix=/usr
@itemx --prefix=/opt/TeXLive
Or whatever your convention is.  The default is @file{/usr/local} and
you shouldn't install there for a distro.

@item --libdir=\$@{exec_prefix@}/lib64
May be needed for 64-bit bi-architecture (GNU/Linux) systems.

@end table

@cindex Preining, Norbert
@cindex adapting @TL{} for distros
You will need to take care of the support files mentioned above
(@pxref{Installing}), and many other issues, such as font maps,
languages, and formats, independently of the build.  Norbert Preining
has written a detailed article on adapting TL for distros:
@url{http://tug.org/TUGboat/tb34-3/tb108preining-distro.pdf}.  (If the
article needs updating in the future, perhaps we will merge it into
this document.)


@node Layout and infrastructure
@chapter Layout and infrastructure

@cindex layout of sources
@cindex source tree

The @TL{} source tree is the subtree rooted at @file{Build/source} of
the complete TL distribution and contains the sources for all executables
distributed by TL, as well as @code{configure} scripts and @code{make}
rules to build and install them together with some of their support
files.

@menu
* Build system tools::          If modifying infrastructure files.
* Top-level directories::
* Autoconf macros::             TL-specific Autoconf macros.
* Library modules::             Details on some specific libraries,
* Program modules::             and on some programs.
* Extending @TL{}::             Adding a new module.
@end menu


@node Build system tools
@section Build system tools

@cindex tools, for building
@cindex GNU tools, needed for building
@cindex infrastructure, tools needed for

As mentioned above (@pxref{Prerequisites}), a normal build requires
very little.  On the other hand, if you want to modify the @TL{}
infrastructure sources, such as @file{configure.ac} or
@file{Makefile.am} files, you will need to have several additional
tools installed.

In general, the TL build system uses the latest released versions of
the GNU build tools, installed directly from the original GNU releases
(e.g., by building them with @code{configure --prefix=/usr/local/gnu}
and having @env{PATH} start with @file{/usr/local/gnu/bin}).  We have
found that trying to use the versions of these tools packaged for
distros causes many extra hassles, so don't do that, tempting as it
may be.

Currently the versions we use are:

@display
@include build-tools.txt
@end display

@pindex reautoconf
@vindex --enable-maintainer-mode configure @r{option}
These versions should be used to update the generated files (e.g.,
@file{configure} or @file{Makefile.in}) in all or parts of the TL tree
after their dependencies have been changed.  This can be done
explicitly with the top-level @code{reautoconf} script or implicitly
by using the configure option @code{--enable-maintainer-mode}.

@cindex Subversion repository
@cindex timestamps, in repository
@vindex use-commit-times@r{, Subversion}
The files in the Subversion repository (see
@url{http://tug.org/texlive/svn}) are all up to date, but
unfortunately this may not be reflected by their timestamps.  (For
starters, be sure to set @file{use-commit-times=yes} in
@file{~/.subversion/config} or the equivalent.)

@cindex touching files to avoid rerunning
@pindex make -t
To avoid unnecessary runs of @code{bison}, @code{flex}, or
@code{makeinfo} it may be necessary to @code{touch} the generated
(@file{.c}, @file{.h}, or @file{.info}) files.  With
@code{--enable-maintainer-mode} it may also be necessary to
@code{touch} first @file{aclocal.m4}, then @file{configure} and
@file{config.h.in} (or @file{c-auto.in}), and finally all
@file{Makefile.in} files.  Perhaps @code{make -t} will help.


@node Top-level directories
@section Top-level directories

@cindex directories, top-level
@cindex top-level directories

Here is a brief description of the top-level directories in the @TL{}
source tree.

As mentioned at the beginning of the chapter (@pxref{Overview of build
system}), the main source directories are @file{texk/}
(@TeX{}-specific programs and libraries), @file{utils/} (additional
programs), and @file{libs} (generic libraries).

@cindex @file{am/} top-level directory
@cindex @file{m4/} top-level directory
The top-level directories @file{am/} and @file{m4/} contain
@file{Makefile.am} fragments and Autoconf macros, respectively, used
in many places.  Specifically, the file @file{m4/kpse-pkgs.m4}
contains lists of all program and library modules; missing modules are
silently ignored.  (This helps in creating cut-down source trees.)

Each module contributes fragments (in separate files) defining its
capabilities and requirements to the @file{configure.ac} scripts at
the top-level and in the subdirectories @file{libs}, @file{utils}, and
@file{texk}.  The fragments from program modules supply
@code{configure} options to disable or enable building them; those
from library modules specify if an installed (system) version of that
library can be used.  This ultimately determines which modules need to
be built---although all modules must be configured for the benefit of
@file{make} targets such as @code{dist} or @code{distcheck}.

@pindex config.guess@r{,} config.sub
@cindex Gnulib, used for common files
The top-level @file{build-aux/} directory contains the common files
@file{compile}, @file{config.guess}, @file{config.sub},
@file{depcomp}, etc.@ for most packages, pulled from the GNU Gnulib
sources (@url{http://www.gnu.org/software/gnulib}), which in turn
synchronizes with the appropriate ultimate upstream repository.  There
are, however, independent copies in, e.g.,
@file{libs/freetype2/freetype-*/builds/unix/}, and similar places.
The @code{reautoconf} script does not touch those, but a TL cron job
keeps them in sync (nightly).

@cindex @file{extra/} top-level directory
The directory @file{extra/} contains things which are not part of the
TL build, but are present just for (someone's) convenience, e.g.,
@file{epstopdf} which is developed here.


@node Autoconf macros
@section Autoconf macros

@cindex autoconf macros

@c Texinfo macro: @ovar(ARG)
@c ARG is the name of an optional argument; this is used for
@c documentation of macro arguments (@defmac lines).  Plain
@c brackets are treated specially and appear more distinct.
@macro ovar{varname}
[@var{\varname\}]
@end macro

@c @dvar(ARG, DEFAULT)
@c -------------------
@c The ARG is an optional argument, defaulting to DEFAULT.  To be used
@c for macro arguments in their documentation (@defmac).
@c @macro xxdvar{varname, default}
@c @r{[}@var{\varname\} = @samp{\default\}@r{]}
@c @end macro

Here we describe some of the Autoconf macros used in several
modules--not a complete list, by any means.  These general macros are
supplemented by module-specific macros in directories such as
@file{texk/dvipng/m4/}; some of those are described in @ref{Library
modules} and @pxref{Program modules}.

@menu
* Setup:     General setup macros.
* Programs:  Macros for programs.
* Compilers: Macros for compilers.
* Libraries: Macros for libraries.
* Flags:     Macros for library and header flags.
* Windows:   Macros for Windows.
@end menu

@node General setup macros
@subsection General setup macros

@cindex general setup macros
@cindex setup macros, general
@cindex macros, general setup
The TL sources use two general setup macros:

@defmac KPSE_BASIC (@var{name}, @ovar{more-options})
Initialize the basic TL infrastructure for module @var{name}:@*@ @ @
@code{AM_INIT_AUTOMAKE([foreign @var{more-options}])}@*@ @ @
@code{AM_MAINTAINER_MODE}@*@ @ @ @code{KPSE_COMPILER_WARNINGS}@*
and make sure the C compiler understands function prototypes.  This is
used for all generic library and program modules.
@end defmac

@defmac KPSE_COMMON (@var{name}, @ovar{more-options})
Like @code{KPSE_BASIC} but add:@*@ @ @ @code{LT_PREREQ([2.2.6])}@*@ @
@ @code{LT_INIT([win32-dll])}@*@ @ @ @code{AC_SYS_LARGEFILE}@*@ @ @
@code{AC_FUNC_FSEEKO}@*and check for frequently used functions,
headers, types, and structures.  This is used for @TeX{}-specific
modules.
@end defmac


@node Macros for programs
@subsection Macros for programs

@cindex macros, for programs
Macros for program checks:

@defmac KPSE_CHECK_LATEX
Set @code{LATEX} to the name of the first of @code{latex},
@code{elatex}, or @code{lambda} which exists in @code{PATH}, or to
@code{no} if none of them exists.  Call @code{AC_SUBST} for
@code{LATEX}.  The result of this test can be overridden by setting
the @code{LATEX} environment variable or the cache variable
@code{ac_cv_prog_LATEX}.
@end defmac

@defmac KPSE_CHECK_PDFLATEX
Check for @code{pdflatex} in @code{PATH} and set @code{PDFLATEX}.
@end defmac

@defmac KPSE_CHECK_PERL
Check for @code{perl} or @code{perl5} in @code{PATH} and set
@code{PERL}.
@end defmac

@defmac KPSE_PROG_LEX
Call @code{AC_PROG_LEX} and add the flag @code{-l} for @code{flex}.
@end defmac


@node Macros for compilers
@subsection Macros for compilers

@cindex macros, for compilers

Macros for compiler-related checks:

@defmac KPSE_COMPILER_WARNINGS
@vindex WARNING_C[XX]FLAGS
When using the (Objective) C/C++ compiler, set
@code{WARNING_[OBJ]C[XX}]FLAGS to suitable warning flags (depending on
the value given to or implied for @code{--enable-compiler-warnings}).
Call @code{AC_SUBST} for them.  At the moment this only works for GNU
compilers, but could be extended to others if necessary.

@vindex kpse_cv_warning_cflags
This macro caches its results in the @code{kpse_cv_warning_cflags},
@dots{} variables.
@end defmac

@defmac KPSE_COMPILER_VISIBILITY
When using the C or C++ compiler, try to set
@code{VISIBILITY_C[XX]FLAGS} to flags to hide external symbols.  Call
@code{AC_SUBST} for this variable.  At the moment this only tests for
the compiler option @code{-fvisibility=hidden}, but that could be
extended with more checks if necessary.

@vindex kpse_cv_visibility_c[xx]flags
This macro caches its results in the @code{kpse_cv_visibility_cflags}
or @code{kpse_cv_visibility_cxxflags} variable.
@end defmac

@defmac KPSE_CXX_HACK
@cindex static linking for C++
@cindex linking C++ libraries statically
@vindex --enable-cxx-runtime-hack configure @r{option}
@pindex libstc++@r{, statically linking}
Provide the configure option @code{--enable-cxx-runtime-hack}.  If
enabled and when using @code{g++}, try to statically link with
@file{libstdc++}, somewhat improving portability of the resulting
binary.

@vindex kpse_cv_cxx_hack
This macro caches its result in the @code{kpse_cv_cxx_hack} variable.
@end defmac


@node Macros for libraries
@subsection Macros for libraries

@cindex macros, for libraries
One macro for a library check:

@defmac KPSE_LARGEFILE (@var{variable}, @ovar{extra-define})
Call @code{AC_SYS_LARGEFILE} and @code{AC_FUNC_FSEEKO} and append
suitable @code{-D} flags (optionally including
@code{-D@var{extra-define}}) to @var{variable}.
@end defmac


@node Macros for library and header flags
@subsection Macros for library and header flags

@cindex macros, for library and header flags
@cindex flags, macros for library and header
@vindex KPSE_@var{LIB}_FLAGS
Each library module @file{libs/@var{lib}} or @file{texk/@var{lib}} is
supplemented by a macro @code{KPSE_@var{LIB}_FLAGS} (all uppercase)
that provides make variables for that library.  E.g., for
@file{libs/libpng}:

@defmac KPSE_LIBPNG_FLAGS
Provide the configure option @code{--with-system-libpng}.  Set and
@code{AC_SUBST} @code{make} variables for modules using this library
(either an installed version or from the @TL{} tree): @code{LIBPNG_INCLUDES}
for use in CPPFLAGS, LIBPNG_LIBS for use in LDADD, LIBPNG_DEPEND for
use as dependency, and LIBPNG_RULE defining @code{make} rules to
rebuild the library.
@end defmac

@defmac KPSE_ADD_FLAGS (@var{libname})
Temporarily extend CPPFLAGS and LIBS with the values required for the
library module @code{@var{name}}.
@end defmac

@defmac KPSE_RESTORE_FLAGS
Restore @code{CPPFLAGS} and @code{LIBS} to their original values.
@end defmac

As an example, the @file{configure.ac} file for a hypothetical program
@file{utils/foo} using @file{libpng}, and hence @file{zlib}, would
contain
@example
KPSE_ZLIB_FLAGS
KPSE_LIBPNG_FLAGS
@end example

@noindent and its @file{Makefile.am} would be along these lines:
@example
bin_PROGRAMS = foo
AM_CPPFLAGS = $@{ZLIB_INCLUDES@} $@{LIBPNG_INCLUDES@}
foo_LDADD = $@{ZLIB_LIBS@} $@{LIBPNG_LIBS@}
foo_DEPENDENCIES = $@{ZLIB_DEPEND@} $@{LIBPNG_DEPEND@}
## Rebuild libz
@@ZLIB_RULE@@
## Rebuild libpng
@@LIBPNG_RULE@@
@end example

If it was necessary to examine whether certain @file{zlib} or
@file{libpng} features were available, @file{configure.ac} should be
continued this way:
@example
KPSE_ADD_FLAGS([zlib])
@dots{} # @r{tests for @file{zlib} features, if any}
KPSE_ADD_FLAGS([libpng])
@dots{} # @r{tests for @file{libpng} features}
KPSE_RESTORE_FLAGS # @r{restore @code{CPPFLAGS} and @code{LIBS}}
@end example


@node Macros for Windows
@subsection Macros for Windows

@cindex macros, for Windows
@cindex Windows, macros for
Windows differs in several aspects from Unix-like systems, many of
them due to the lack of symbolic links.

@defmac KPSE_CHECK_WIN32
@vindex kpse_cv_have_win32
Check if compiling for a Windows system.  The result is @code{no} for
Unix-like systems (including Cygwin), @code{mingw32} for Windows with
GCC, or @code{native} for Windows with MSVC.  The result is cached in
the @code{kpse_cv_have_win32} variable.
@end defmac

@defmac KPSE_COND_WIN32
@vindex WIN32@r{, Automake conditional}
Call @code{KPSE_CHECK_WIN32} and define the Automake conditional
@code{WIN32} (@code{true} if the value of @code{kpse_cv_have_win32} is
not @code{no}).
@end defmac

@defmac KPSE_COND_MINGW32
@vindex MINGW32@r{, Automake conditional}
Call @code{KPSE_COND_WIN32} and define the Automake conditional
@code{MINGW32} (@code{true} if the value of @code{kpse_cv_have_win32} is
@code{mingw32}).
@end defmac

@defmac KPSE_COND_WIN32_WRAP
@vindex WIN32_WRAP@r{, Automake conditional}
@pindex runscript.exe
Call @code{KPSE_COND_WIN32} and define the Automake conditional
@code{WIN32_WRAP} (@code{true} if the standard Windows wrapper
(@file{texk/texlive/w32_wrapper/runscript.exe}) exists.  This wrapper
is used on Windows instead of symlinks for the ``linked scripts''
(@pxref{Linked scripts}).
@end defmac

@defmac KPSE_WIN32_CALL
@pindex callexe.c
Call @code{KPSE_COND_WIN32}, check if the file
@file{texk/texlive/w32_wrapper/callexe.c} exists; if it does, create a
symlink in the build tree.  Compiling @file{callexe.c} with
@code{-DEXEPROG='"@var{foo}.exe"'} and installing @file{callexe.exe}
as @code{@var{bar}.exe} is used on Windows instead of a symlink
@code{@var{bar}->@var{foo}} for Unix-like systems.
@end defmac


@node Library modules
@section Library modules

@cindex library modules
@cindex modules, for libraries
Here we discuss some specifics for a few of the libraries in TL, both
for the details themselves, and as a way of illuminating the general
structure and variation.

@menu
* @code{png} library::       @file{libs/libpng}
* @code{zlib} library::      @file{libs/zlib}
* @code{freetype} library::  @file{libs/freetype2}
* @code{kpathsea} library::  @file{texk/kpathsea}
@end menu

@node @code{png} library
@subsection The @code{png} library in @file{libs/libpng}

@pindex png @r{library}
@pindex libpng @r{library}
This generic library uses the source tree in, e.g., the subdirectory
@file{libpng-1.5.17} with all modifications for TL recorded in
@file{libpng-1.5.17-PATCHES/*}.  The @file{configure.ac} fragment
@file{ac/withenable.ac} contains

@example
KPSE_WITH_LIB([libpng], [zlib])
@end example

@noindent specifying the module name, and indicating the dependency on
@code{zlib}.  A third literal argument @code{tree} would specify that
the library from the @TL{} tree cannot be replaced by a system
version.  That not being the case here, a second fragment
@file{ac/libpng.ac} contains

@findex KPSE_TRY_LIB
@example
KPSE_TRY_LIB([libpng],
             [#include <png.h>],
             [png_structp png; png_voidp io; png_rw_ptr fn;
png_set_read_fn(png, io, fn);])
@end example

@noindent thus providing the simple C code

@example
#include <png.h>
int main ()
@{ png_structp png; png_voidp io; png_rw_ptr fn;
  png_set_read_fn(png, io, fn);
  return 0; @}
@end example

@findex KPSE_TRY_LIBXX
@noindent which Autoconf uses to verify the usability of a system
version with C code.  The analogous macro @code{KPSE_TRY_LIBXX} would
check using C++ code.  These fragments are included by
@file{configure.ac} at the top level.

For this library, among many other modules, a proxy build system for
TL is used (@file{configure.ac}, @file{Makefile.am}, and
@file{include/Makefile.am}), ignoring the distributed one.
Consequently, a few generated files and auxiliary scripts are removed
from the distributed source tree.  The public headers @file{png.h},
@file{pngconf.h}, and @file{pnglibconf.h} are ``installed'' (as
symlinks) under @file{include/} in the build tree exactly as they are
for a system version under, e.g., @file{/usr/include/}.

@pindex kpse-libpng-flags.m4
@vindex KPSE_LIBPNG_FLAGS
The module is supplemented by the file @file{m4/kpse-libpng-flags.m4}
that defines the M4 macro @code{KPSE_LIBPNG_FLAGS} used by all modules
depending on this library in their @file{configure.ac} to generate the
@code{make} variables @code{LIBPNG_INCLUDES} for use in
@code{CPPFLAGS}, @code{LIBPNG_LIBS} for use in @code{LDADD},
@code{LIBPNG_DEPEND} for use as dependencies, and @code{LIBPNG_RULE}
defining @code{make} rules to rebuild the library.

@file{m4/kpse-libpng-flags.m4} also supplies the configure option
@code{--with-system-libpng} and uses @code{pkg-config} to determine
the flags required for the system library.


@node @code{zlib} library
@subsection The @code{zlib} library in @file{libs/zlib}

@pindex zlib @r{library}

@pindex kpse-zlib-flags.m4
This generic library is very much analogous to @code{libpng}, but
without the dependency on any other library.  The file
@file{m4/kpse-zlib-flags.m4} supplies the configure option
@code{--with-system-zlib}, as well as @code{--with-zlib-includes} and
@code{--with-zlib-libdir} to specify non-standard locations of the
@code{zlib} headers and/or library.


@node @code{freetype} library
@subsection The @code{freetype} library in @file{libs/freetype2}

@pindex freetype @r{library}

@pindex freetype-config
This module uses a wrapper build system with an almost trivial
@file{configure.ac} and with a @file{Makefile.am} that invokes
@code{configure} and @code{make} for the distributed source, followed
by @code{make install} with the build tree as destination.  The flags
required for the system library are obtained through
@code{freetype-config}.


@node @code{kpathsea} library
@subsection The @code{kpathsea} library in @file{texk/kpathsea}

@pindex kpathsea @r{library}

This is one of the @TeX{}-specific libraries that are maintained as
part of @TL{} (@pxref{,,, kpathsea, Kpathsea}).  Despite being a core
part of the @TeX{} system, it is not a terribly special case in the
infrastructure.  The @TeX{} libraries are Libtool libraries (static
and/or shared) and are installed by @code{make install} together with
the programs.  They are, however, not part of the TL DVD as
distributed by @TeX{} user groups, and have never been officially
released for standalone use.

@pindex --with-system-kpathsea
It is possible, and possibly even useful for distro builds
(@pxref{Distro builds}, to specify the configure option
@code{--with-system-kpathsea} in order to use a system version of the
library and it may then be necessary to specify
@code{--with-kpathsea-includes} and/or @code{--with-kpathsea-libdir}.

@pindex kpathsea.ac
@pindex mktex.ac
@vindex --enable-mktextfm-default
@pindex mktextfm
In addition to @file{ac/withenable.ac} and @file{ac/kpathsea.ac} there
is a third fragment @file{ac/mktex.ac} included by both
@file{ac/withenable.ac} and @file{configure.ac} that supplies
configure options such as @code{--enable-mktextfm-default}, which
determine the compile time default of whether or not to run
@code{mktextfm} to generate a missing @file{.tfm} file.  In any case,
however, the command line options @code{-mktex=tfm} or
@code{-no-mktex=tfm} for the @TeX{}-like engines override this default.


@node Program modules
@section Program modules

@cindex program modules
@cindex modules, for programs
As with libraries (@pxref{Library modules}), here we discuss the
details for a few of the programs in TL.

@menu
* @code{t1utils} package:: @file{utils/t1utils}
* @code{xindy} package::   @file{utils/xindy}
* @code{xdvik} package::   @file{texk/xdvik}
* @code{asymptote}::       @file{utils/asymptote}
@end menu


@node @code{t1utils} package
@subsection The @code{t1utils} package in @file{utils/t1utils}

@pindex t1utils @r{package}

Once again we use the distributed source tree @file{t1utils-1.38} with
modifications documented in @file{t1utils-1.38-PATCHES/*} and a proxy
build system consisting of @file{configure.ac} and @file{Makefile.am}.
The fragment @file{ac/withenable.ac} contains

@example
KPSE_ENABLE_PROG([t1utils])
@end example

@noindent specifying the module name without any dependencies, and
supplies the configure option @code{--disable-t1utils}.


@node @code{xindy} package
@subsection The @code{xindy} package in @file{utils/xindy}

@pindex xindy

This module uses the distributed source tree @file{xindy-2.4} with
modifications documented in @file{xindy-2.4-PATCHES/*}, a proxy
@file{configure.ac}, and a wrapper @file{Makefile.am} that descends
into @file{xindy-2.4}.  The @code{xindy} build requires that the
distributed @file{Makefile}s allow a @code{VPATH} build, can handle
all targets, and do not refer to @code{$@{top_srcdir@}} or
@code{$@{top_builddir@}}.  The fragment @code{ac/withenable.ac}
contains

@example
KPSE_ENABLE_PROG([xindy], , [disable native])
m4_include(kpse_TL[utils/xindy/ac/xindy.ac])
m4_include(kpse_TL[utils/xindy/ac/clisp.ac])
@end example

@noindent where @code{disable} in the third argument indicates that
@code{xindy} is only built if explicitly enabled by the user with
@code{configure --enable-xindy} (the need for @code{clisp} is too
painful to require by default), and @code{native} disallows cross
compilation.  The additional fragments @file{ac/xindy.ac} and
@file{ac/clisp.ac} specify more @code{configure} options to be seen at
the top level with @file{ac/xindy.ac} also included by
@file{configure.ac}.


@node @code{xdvik} package
@subsection The @code{xdvik} package in @file{texk/xdvik}

@pindex xdvik

This package is maintained as part of the @TL{} tree with sources in
its top level directory and the subdirectory @file{gui}.  The fragment
@code{ac/withenable.ac} contains

@example
dnl extra_dirs = texk/xdvik/squeeze
KPSE_ENABLE_PROG([xdvik], [kpathsea freetype2], [x])
m4_include(kpse_TL[texk/xdvik/ac/xdvik.ac])
@end example

@pindex squeeze/configure.ac
@cindex cross compilation, with host binary
@noindent thus specifying the dependency on the @code{kpathsea},
@code{freetype}, and X11 libraries.  The M4 comment (following
@code{dnl}) signals the subsidiary @file{squeeze/configure.ac}.  This
is needed because the main executable @file{xdvi-bin} (to be installed
as, e.g., @file{xdvi-xaw}) is for the @code{host} system whereas the
auxiliary program @file{squeeze/squeeze} has to run on the
@code{build} system and in a cross compilation they differ.

@vindex --with-xdvi-x-toolkit
The additional fragment @code{ac/xdvik.ac} is also included by
@file{configure.ac} and supplies the configure option
@code{--with-xdvi-x-toolkit} also seen at the top-level.


@node @code{asymptote}
@subsection The subdirectory @file{utils/asymptote}

@pindex asymptote
@pindex xasy

@cindex OpenGL, required for Asymptote
This subdirectory contains the sources for @file{asy} and @file{xasy}
but due to its complexity and prerequisites (e.g., OpenGL) it is
not part of the TL build system.  These programs must be built and
installed independently, but are included on the TL DVD together with
their support files.


@node Extending @TeX{} Live
@section Extending @TeX{} Live

@cindex extending @TL{}
@cindex adding to @TL{}

This section outlines the basic process for adding new packages to the
TL build system.

@menu
* Adding a new program module::
* Adding a new generic library module::
* Adding a new @TeX{}-specific library module::
@end menu


@node Adding a new program module
@subsection Adding a new program module

@cindex adding a new program
@cindex program module, adding

@vindex kpse_texk_pkgs
A @TeX{}-specific program module in a subdirectory
@file{texk/@var{prog}} may use the @TeX{}-specific libraries and is
included by adding its name @file{@var{prog}} to the M4 list
@code{kpse_texk_pkgs} defined in @file{m4/kpse-pkgs.m4}.

@vindex kpse_utils_pkgs
A generic program module in a subdirectory @file{utils/@var{prog}}
must not use the @TeX{}-specific libraries and is included by adding
its name @file{@var{prog}} to the M4 list @code{kpse_utils_pkgs} in
@file{m4/kpse-pkgs.m4}.

@pindex withenable.ac@r{, for new modules}
@findex KPSE_ENABLE_PROG
In either case, apart from the program sources and build system
(@file{configure.ac} and @file{Makefile.am}), the subdirectory
@file{texk/@var{prog}} or @file{utils/@var{prog}} must provide a
fragment @file{ac/withenable.ac} that contains the M4 macro
@code{KPSE_ENABLE_PROG} defined in @file{m4/kpse-setup.m4} with
@code{@var{prog}} as the mandatory first argument and three optional
arguments:

@enumerate
@item a list of required libraries from the TL tree;

@item a list of options (@code{disable} if this module is not to be
built without the configure option @code{--enable-@var{prog}},
@code{native} if cross compilation is not possible, @code{x} if the
program requires X11 libraries);

@item and a comment added to the help text for the @code{configure}
option @code{--enable-@var{prog}} or @code{--disable-@var{prog}}.
@end enumerate

If the module requires specific configure options to be seen at the
top-level, they should be defined in an additional fragment
@file{ac/@var{prog}.ac} included from @file{ac/withenable.ac} and
@file{configure.ac}.


@node Adding a new generic library module
@subsection Adding a new generic library module

@cindex adding a new generic library
@cindex generic library module, adding
@cindex library module, generic, adding

@vindex kpse_libs_pkgs
A generic library module in a subdirectory @file{libs/@var{lib}} must
not depend on @TeX{}-specific libraries, by definition.  It is
included by adding its name @file{@var{lib}} to the M4 list
@code{kpse_libs_pkgs} in @file{m4/kpse-pkgs.m4}---before any other
libraries from the @TL{} tree on which it depends.

@findex KPSE_WITH_LIB
As with program modules, the subdirectory @file{libs/@var{lib}} must
contain the sources and build system for the library (and any
installable support programs) and a fragment @file{ac/withenable.ac}
that contains the M4 macro @code{KPSE_WITH_LIB} defined in
@file{m4/kpse-setup.m4} with @code{@var{lib}} as the mandatory first
argument and two optional arguments: a list of required libraries from
the TL tree, and a list of options (currently there is only one:
specify @code{tree} if this library cannot be replaced by a system
version).

@findex KPSE_TRY_LIB
@findex KPSE_TRY_LIBXX
If a system version can be used, a second fragment
@file{ac/@var{lib}.ac} is needed, containing the M4 macro
@code{KPSE_TRY_LIB} (or @code{KPSE_TRY_LIBXX}) with @code{@var{lib}}
as the mandatory first argument and two additional arguments for the
Autoconf macro @code{AC_LANG_PROGRAM} used to compile and link a small
C (or C++) program as sanity check for using the system library.

@vindex KPSE_@var{LIB}_FLAGS
In addition a file @file{m4/kpse-@var{lib}-flags} (at the top level)
must define the M4 macro @code{KPSE_@var{LIB}_FLAGS} (all uppercase)
setting up the @code{make} variables @code{@var{LIB}_INCLUDES},
@code{@var{LIB}_LIBS}, @code{@var{LIB}_DEPEND}, and
@code{@var{LIB}_RULE} with the values required for @code{CPPFLAGS},
@code{LDADD}, dependencies, and a (multi-line) @code{make} rule to
rebuild the library when necessary.  All of that is needed for the
library from the TL tree and, if supported, for a system version.

@vindex --with-system-@var{lib}
@vindex KPSE_@var{LIB}_SYSTEM_FLAGS
@vindex KPSE_ALL_SYSTEM_FLAGS
If a system library is allowed, @code{KPSE_@var{LIB}_FLAGS} also
provides the configure option @code{--with-system-@var{lib}} and uses
the additional M4 macro @code{KPSE_@var{LIB}_SYSTEM_FLAGS} to generate
the @code{make} variables for a system library.  Furthermore the
definition of the M4 macro @code{KPSE_ALL_SYSTEM_FLAGS} in
@file{m4/kpse-pkgs.m4} must be extended by the line:@*@ @ @
@code{AC_REQUIRE([KPSE_@var{LIB}_SYSTEM_FLAGS])}


@node Adding a new @TeX{}-specific library module
@subsection Adding a new @TeX{}-specific library module

@cindex adding a new @TeX{}-specific library
@cindex @TeX{}-specific library module, adding
@cindex library module, @TeX{}-specific, adding

A @TeX{}-specific library module in a subdirectory
@file{texk/@var{lib}} may depend on other @TeX{}-specific libraries
but must not depend on any generic library from the TL tree.  It is
included in the same general ways as a generic library (see the
previous section), with these modifications:

@itemize @bullet
@item
@vindex kpse_texlibs_pkgs
The library name @code{@var{lib}} is added to the M4 list
@code{kpse_texlibs_pkgs} also in @file{m4/kpse-pkgs.m4}.

@item
@findex KPSE_WITH_TEXLIB
The fragment @code{ac/withenable.ac} must use @code{KPSE_WITH_TEXLIB}.
@end itemize


@node Configure options
@chapter Configure options

@cindex @code{configure} options

Corresponding to the large number of program and library modules there
are a large number @code{configure} options, most of which are
described here.  The command@*@ @ @ @code{configure --help}@*at the
top level gives an exhaustive list of all global options and a few
important module-specific ones, whereas, e.g.,@*@ @ @
@code{texk/lcdf-typetools/configure --help}@* also displays the
@code{lcdf-typetools} specific options, which are not shown by the
top-level @code{--help}.

@cindex environment variables, for @code{configure}
The help text also mentions several influential environment variables,
but for @TL{} it is better to specify them as assigments on the
command line.

The @file{./Build} script used to make the binaries shipped with @TL{}
invokes the top-level @code{configure} with a few additional options
(@pxref{Building}).  The defaults discussed below are those for the
actual @code{configure} script; invoking @code{configure} via
@file{./Build} may yield different results.

Defaults for most options are set at the top level and propagated
explicitly to all subdirectories.  Options specified on the command
line are checked for consistency but never modified.

@menu
* Global configure options::
* Program-specific configure options::
* Library-specific configure options::
* Variables for configure::
@end menu


@node Global configure options
@section Global configure options

@cindex global @code{configure} options
@cindex @code{configure} options, global
Here are the global configure options.

@menu
* @code{--disable-native-texlive-build}::
* @code{--prefix} @code{--bindir} @dots{}::
* @code{--disable-largefile}::
* @code{--disable-missing}::
* @code{--enable-compiler-warnings=}@var{level}::
* @code{--enable-cxx-runtime-hack}::
* @code{--enable-maintainer-mode}::
* @code{--enable-multiplatform}::
* @code{--enable-shared}::
* @code{--enable-silent-rules}::
* @code{--without-ln-s}::
* @code{--without-x}::
@end menu


@node @code{--disable-native-texlive-build}
@subsection @code{--disable-native-texlive-build}

@vindex --disable-native-texlive-build
If enabled (the default), build for a TL binary distribution as
shipped by the @TeX{} user groups.  This requires GNU @code{make} and
implies @code{--enable-multiplatform} and
@code{--enable-cxx-runtime-hack} (unless they are explicitly disabled),
and enforces @code{--disable-shared}.

If building TL for a GNU/Linux or other distribution, this should be
disabled and system versions of most libraries would be used
(@pxref{Distro builds}).  This may fail without GNU @code{make}, but
will be tried regardless.

@vindex --enable-texlive-build
A related option, @code{--enable-texlive-build}, is automatically
passed to all subdirectories (and cannot be disabled).  Subdirectories
that can also be built independently from the TL tree (such as
@file{utils/xindy} and @file{texk/dvipng}) can use this option, e.g.,
to choose TL-specific installation paths.


@node @code{--prefix} @code{--bindir} @dots{}
@subsection @code{--prefix}, @code{--bindir}, @dots{}

@vindex --prefix configure @r{option}
@vindex --bindir configure @r{option}
These standard Autoconf options specify various installation
directories as usual.  For the complete list, @pxref{Installation
directories}.

@vindex DESTDIR
Also as usual, all values are prefixed by the value of @code{DESTDIR},
if set, on the @code{make} command line (@pxref{Staged Installs, ,
Installation in a temporary location, automake, GNU Automake}).


@node @code{--disable-largefile}
@subsection @code{--disable-largefile}

@vindex --disable-largefile
@cindex large file support
@cindex LFS (large file support)
Omit large file support (LFS), needed on most 32-bit Unix systems for
files with 2GB or more.  Regardless of this, the size of @code{DVI}
and @code{GF} files must always be @math{<2}GB, due to the file format
specifications.

@cindex size of PDF and PS files
@cindex PDF files, size of
@cindex PostScript files, size of
With LFS, there is no fixed limit on the size of PDF files created by
@file{pdftex} or PostScript files created by @file{dvips}.  The size
of PDF images included by @file{pdftex} must, however, be @math{<4}GB
when using @file{xpdf} and @math{<2}GB when using older versions of
@file{poppler} (even on 64-bit systems with LFS), whereas
@file{poppler} versions@tie{}0.23 and later impose no such limit.


@node @code{--disable-missing}
@subsection @code{--disable-missing}

@vindex --disable-missing
Immediately terminate the build process if a requested program or feature
must be disabled, e.g., due to missing libraries.  This can help when
figuring out a specific (sub)set of modules to enable.


@node @code{--enable-compiler-warnings=}@var{level}
@subsection @code{--enable-compiler-warnings=}@var{level}

@vindex --enable-compiler-warnings=@var{level}
Enable various levels of compiler warnings for (Objective) C and C++:
the @var{level} value can be one of: @code{no min yes max all}.
The default is @code{yes} in @code{maintainer-mode} (see below) and
@code{min} otherwise.  This option defines
@code{WARNING_[OBJ]C[XX]FLAGS} but these flags are not used in all
library and program modules.  Using them should help to resolve
portability problems.

At present, these warning flags are only defined for the GNU compilers
but flags for other compilers could be added when needed.


@node @code{--enable-cxx-runtime-hack}
@subsection @code{--enable-cxx-runtime-hack}

If enabled (as it is for the native TL build) and when using
@code{g++}, try to statically link with @code{libstdc++}, somewhat
improving portability of the resulting binary.  @xref{Macros for
compilers}.


@node @code{--enable-maintainer-mode}
@subsection @code{--enable-maintainer-mode}

@vindex --enable-maintainer-mode
Enable @file{make} rules and dependencies not useful (and sometimes
confusing) to the casual user.  This requires current versions of the
GNU build tools (@pxref{Build system tools}), as it automatically
rebuilds infrastructure files as needed.  @xref{maintainer-mode,,
@code{missing} and @code{AM_MAINTAINER_MODE}, automake, GNU Automake}.


@node @code{--enable-multiplatform}
@subsection @code{--enable-multiplatform}

@vindex --enable-multiplatform
@vindex exec_prefix
@vindex --libdir
If enabled, install executables and libraries in per-platform
subdirectories of @file{@var{eprefix}/bin} and
@file{@var{eprefix}/lib} where @var{eprefix} is the value given or
implied for @code{exec_prefix}.  This can be overridden by explicitly
@code{--bindir=@var{dir}} or @code{--libdir=@var{dir}}.  In any case,
the values for @code{bindir} and @code{libdir} are automatically
propagated to all subdirectories.


@node @code{--enable-shared}
@subsection @code{--enable-shared}

@vindex --enable-shared
Build shared versions of the @TeX{}-specific libraries such as
@file{libkpathsea}.  This is not allowed for a native TL build (i.e.,
@code{--disable-native-texlive-build} must also be specified).


@node @code{--enable-silent-rules}
@subsection @code{--enable-silent-rules}

@vindex --enable-silent-rules
Enable the use of less verbose build rules.  When using GNU
@code{make} (or another @code{make} implementation supporting nested
variable expansions), you can specify @code{V=1} on the @code{make} command
line to get more verbosity, or @code{V=0} to get less, regardless of
this option.


@node @code{--without-ln-s}
@subsection @code{--without-ln-s}

@vindex --without-ln-s
Required when using a system without a working @code{ln -s} to build
binaries for a Unix-like system.  However, @code{make install} will
not create anything useful and might even fail.


@node @code{--without-x}
@subsection @code{--without-x}

@vindex --without-x
Disable all programs using the X Window System.


@node Program-specific configure options
@section Program-specific configure options

@cindex program-specific @code{configure} options
@cindex @code{configure} options, program-specific
Here are (some of) the program-specific @code{configure} options.

@menu
* @code{--enable-@var{prog}} @code{--disable-@var{prog}}::
* @code{--disable-all-pkgs}::
* Configure options for @file{texk/web2c}::
* Configure options for @file{texk/bibtex-x}::
* Configure options for @file{texk/dvipdfm-x}::
* Configure options for @file{texk/dvisvgm}::
* Configure options for @file{texk/texlive}::
* Configure options for @file{texk/xdvik}::
* Configure options for @file{utils/xindy}::
@end menu


@node @code{--enable-@var{prog}} @code{--disable-@var{prog}}
@subsection @code{--enable-@var{prog}}, @code{--disable-@var{prog}}

@vindex --enable-@var{prog}
@vindex --disable-@var{prog}
Do or do not build and install the program(s) of the module @code{@var{prog}}.


@node @code{--disable-all-pkgs}
@subsection @code{--disable-all-pkgs}

@vindex --disable-all-pkgs
Do not build any program modules by default---only those explicitly
enabled.  This is useful when one wants to work on only a single
program, which is specified with an additional @code{--enable} option,
e.g., @code{--enable-dvipdfm-x}.  It's still simplest to check out and
configure the whole source tree, but at least only the program you are
interested in, and its dependencies, are built.  The @code{configure}
will generally take less than a minute with everything disabled.  (It
is a good idea to run @code{make check} after doing this, and after
making any changes, to ensure that whatever tests have been written
still pass.)

Without this option, all modules are built except those that are
explicitly disabled or specify @code{disable} in their
@file{ac/withenable.ac} fragment.


@node Configure options for @file{texk/web2c}
@subsection Configure options for @file{texk/web2c}

@cindex @code{configure} options, for @code{web2c}

@vindex --with-banner-add=@var{str}
@noindent @code{--with-banner-add=@var{str}}@*Add @code{@var{str}} to the
default version string (@code{TeX Live @var{year}} or @code{Web2C
@var{year}}) appended to banner lines.  This is ignored for a native
TL build, but distro builds should specify, e.g.,
@code{/@var{SomeDistro}}.

@vindex --with-editor=@var{cmd}
@noindent @code{--with-editor=@var{cmd}}@*Specify the command
@code{@var{cmd}} to invoke from the @code{e} option of @TeX{}-like engines,
replacing the default @code{vi +%d '%s'} for Unix or @code{texworks
--position=%d "%s"} for Windows.

@vindex --with-fontconfig-includes=@var{dir}
@vindex --with-fontconfig-libdir=@var{dir}
@noindent @code{--with-fontconfig-includes=@var{dir}},
@code{--with-fontconfig-libdir=@var{dir}}@*Building Xe@TeX{} on
non-Mac systems requires the @code{fontconfig} library headers and
code.  If one or both of these options are given, the required flags
are derived from them; otherwise, they are determined via
@file{pkg-config} (if present).

@cindex X toolkit
@pindex libXt
@pindex Xlib
@noindent @code{--with-mf-x-toolkit}@*Use the X toolkit (@file{libXt}) for
Metafont (the default is to use the lowest-level @file{Xlib} support;
it seems this has the best chance of working across X installations
nowadays).

@vindex --disable-dump-share
@cindex LittleEndian architectures
@noindent @code{--disable-dump-share}@*Make the @code{fmt}/@code{base}
dump files architecture dependent (somewhat faster on LittleEndian
architectures).

@vindex --disable-ipc
@cindex interprocess communication
@noindent @code{--disable-ipc}@*Disable @TeX{}'s @code{--ipc} option.

@vindex --disable-mf-nowin
@pindex mf-nowin
@noindent @code{--disable-mf-nowin}@*Do not build a separate
non-graphically-capable Metafont (@file{mf-nowin}).

@vindex --disable-omfonts
@pindex opl2ofm@r{, et al.}
@noindent @code{--disable-omfonts}@*Build the WEB versions of the
Omega font utilities @file{ofm2opl}, @file{opl2ofm}, @file{ovf2ovp},
and @code{ovp2ovf} instead of the C version @file{omfonts}. The WEB
and C versions should be roughly equivalent.

@vindex --disable-tex
@vindex --enable-etex
@pindex web2c.ac
@noindent @code{--disable-tex}, @code{--enable-etex}, @dots{}@*Do not or
do build the various @TeX{}, Metafont, and MetaPost engines (defaults are
defined in the fragment @file{texk/web2c/ac/web2c.ac}).

@vindex --disable-web-progs
@noindent @code{--disable-web-progs}@*Do not build the core WEB programs
@file{bibtex}, @dots{}, @file{weave}.  Useful if, e.g., you only want
to (re)build some engines.

@vindex --enable-auto-core
@cindex preloaded binaries
@noindent @code{--enable-auto-core}@*This option causes @TeX{} and Metafont
to produce a core dump when a particular hacky filename is
encountered, for use in creating preloaded binaries.  This is rarely
done nowadays.

@vindex --enable-libtool-hack
@pindex libtool@r{, hack for avoiding excessive linking}
@noindent @code{--enable-libtool-hack}@*
If enabled (which is the default for all platforms), prevents
@code{libtool} from linking explicitly with dependencies of
@file{libfontconfig} such as @file{libexpat}.

@vindex --enable-*win @r{for Metafont window support}
@noindent @code{--enable-*win}@*Include various types of other window
support for Metafont (EPSF output, @code{mftalk}, old terminals, @dots{}).

@vindex --enable-tex-synctex
@vindex --disable-etex-synctex
@cindex synctex
@noindent @code{--enable-tex-synctex}, @code{--disable-etex-synctex},
@dots{}@*Build the @TeX{} engines with or without @code{SyncTeX}
support; ignored for a native @TL{} build, defaults are again defined
in @file{texk/web2c/ac/web2c.ac}.


@node Configure options for @file{texk/bibtex-x}
@subsection Configure options for @file{texk/bibtex-x}

@cindex @code{configure} options, for @code{bibtex-x}
@pindex bibtex8
@pindex bibtexu
@pindex bibtex-x
The former programs @code{bibtex8} and @code{bibtexu} have been merged
into the module @code{bibtex-x} (extended Bib@TeX{}).

@vindex --disable-bibtex8
@noindent @code{--disable-bibtex8}@*Do not build the @file{bibtex8} program.

--disable-bibtexu
@noindent @code{--disable-bibtexu}@*Do not build the @file{bibtexu} program
(building @file{bibtexu} requires @code{ICU} libraries).


@node Configure options for @file{texk/dvipdfm-x}
@subsection Configure options for @file{texk/dvipdfm-x}

@cindex @code{configure} options, for @code{dvipdfm-x}
@pindex dvipdfmx
@pindex xdvipdfmx

The former modules @code{dvipdfmx} (extended DVI to PDF converter) and
@code{xdvipdfmx} (the same, as used by Xe@TeX{}) have been merged into
@code{dvipdfm-x} at the source level.  Two separate binaries are still
created by default.  In addition, @file{dvipdfm} is created as a
symlink to @file{dvipdfmx}, with backward-compatible (very slightly
different) behavior.

@vindex --disable-dvipdfmx
@noindent @code{--disable-dvipdfmx}@*Do not build the @file{dvipdfmx}
program or create the @file{dvipdfm} symlink.

@vindex --disable-xdvipdfmx
@noindent @code{--disable-xdvipdfmx}@*Do not build the @file{xdvipdfmx}
program (building @file{xdvipdfmx} requires the @code{freetype} library).


@node Configure options for @file{texk/dvisvgm}
@subsection Configure options for @file{texk/dvisvgm}

@cindex @code{configure} options, for @file{dvisvgm}
@pindex dvisvgm

@vindex --with-system-libgs
@noindent @code{--with-system-libgs}@*Build @file{dvisvgm} using installed
Ghostscript (@code{gs}) headers and library (not allowed for a native
TL build).  The default is to load the @code{gs} library at runtime if
possible, or otherwise disable support for PostScript specials.

@vindex --without-libgs
@noindent @code{--without-libgs}@*Build @file{dvisvgm} without PostScript
support at all.  Because the dynamic loading just mention defeats all
attempts at static linking, the result can crash due to library
incompatibilities, e.g., on CentOS 5.

@vindex --with-libgs-includes@r{,} -libdir
@noindent @code{--with-libgs-includes=@var{dir}},
@code{--with-libgs-libdir=@var{dir}}@*Specify non-standard locations
of the Ghostscript headers and library.


@node Configure options for @file{texk/texlive}
@subsection Configure options for @file{texk/texlive}

@cindex @code{configure} options, for @file{texk/texlive}
@vindex --disable-linked-scripts
@noindent @code{--disable-linked-scripts}@*Do not install the ``linked
scripts'' (@pxref{Linked scripts}), except for the TL scripts required
to run @code{texlinks}.


@node Configure options for @file{texk/xdvik}
@subsection Configure options for @file{texk/xdvik}

@cindex @code{configure} options, for @file{xdvik}
@pindex xdvik

@vindex --with-gs=@var{filename}
@noindent @code{--with-gs=@var{filename}}@*Hardwire the location of Ghostscript
(@file{gs}).

@vindex --with-xdvi-x-toolkit=@var{kit}
@pindex motif
@pindex xaw
@noindent @code{--with-xdvi-x-toolkit=@var{kit}}@*Use toolkit
@code{@var{kit}} for @file{xdvik}, one of: @code{motif xaw xaw3d
neXtaw}.  The default is @code{motif} if available, else @code{xaw}.

@vindex --enable-xi2-scrolling
@pindex XInput
@pindex scrolling
@noindent @code{--enable-xi2-scrolling}@*Use XInput 2.1 ``smooth scrolling''
if available.  (default: yes, except for a native TL build).


@node Configure options for @file{utils/xindy}
@subsection Configure options for @file{utils/xindy}

@cindex @code{configure} options, for @file{xindy}
@pindex xindy

@vindex --enable-xindy-rules
@noindent @code{--enable-xindy-rules}@*Build and install @code{xindy} rules
(default: yes, except for a native TL build).

@vindex --enable-xindy-docs
@noindent @code{--enable-xindy-docs}@*Build and install @code{xindy}
documentation (default: yes, except for a native TL build).

@vindex --with-clisp-runtime=@var{filename}
@pindex lisp.run@r{,} lisp.exe
@cindex CLISP
@noindent @code{--with-clisp-runtime=@var{filename}}@*Specifies the
Full path for the CLISP runtime file (@file{lisp.run} or
@file{lisp.exe}) to be installed.  When specified as @code{default}
(the default for a native TL build) the path is determined by the
CLISP executable; the value @code{system} (not allowed for a native TL
build, but the default for a non-native one) indicates that
@file{xindy} will use the installed version of @file{clisp} (which
must be identical to the one used to build @file{xindy}).

@vindex --with-recode
@pindex recode
@pindex iconv
@noindent @code{--with-recode}@*Use @file{recode} instead of @file{iconv}
to build the @code{xindy} rules and documentation, required for some
systems where @file{iconv} is missing or broken.


@node Library-specific configure options
@section Library-specific configure options

@cindex library-specific @code{configure} options
@cindex @code{configure} options, library-specific
Here are (some of) the library-specific @code{configure} options,
starting with this generic one:

@vindex --with-system-@var{lib}
@noindent @code{--with-system-@var{lib}}

Use an installed (system) version of the library @code{@var{lib}};
this option exists for most libraries, but is not allowed for a native
TL build.  Using a system version implies also using the system
versions of all libraries (if any) that @var{lib} depends on.

@vindex --with-@var{lib}-includes=@var{dir}@r{,} -libdir
For many libraries @code{--with-@var{lib}-includes=@var{dir}} and
@code{--with-@var{lib}-libdir=@var{dir}} to specify non-standard
search locations; others use @file{pkg-config} or similar to determine
the required flags.

The top-level @file{configure} script performs a consistency check for all
required system libraries and bails out if tests fail.

@menu
* Configure options for @code{kpathsea}::
* Configure options for system @code{poppler}::
@end menu


@node Configure options for @code{kpathsea}
@subsection Configure options for @code{kpathsea}

@cindex @code{configure} options, for @code{kpathsea}

@noindent @code{--enable-@var{cmd}-default},
@code{--disable-@var{cmd}-default}@*Determine the compile time default
whether or not to run @var{cmd}, one of:
@table @code
@item mkocp
(Omega compiled translation process file)
@item mkofm
(Omega font metrics file)
@item mktexfmt
(format/base dump file)
@item mktexmf
(Metafont source)
@item mktexpk
(PK bitmap font)
@item mktextex
(@TeX{} source)
@item mktextfm
(TFM file)
@end table

@noindent to generate the specified type of file dynamically.
The default can be overridden by the user in any case.


@node Configure options for system @code{poppler}
@subsection Configure options for system @code{poppler}

@cindex @code{configure} options, for system @code{poppler}

@pindex poppler
@pindex xpdf @r{as library}
Building Lua@TeX{} and Xe@TeX{} requires @code{poppler}, either from
the TL tree or system headers and library.  Building pdf@TeX{}
requires either @code{xpdf} from the @TL{} tree or system
@code{poppler} headers and library.

@vindex --with-system-poppler
@noindent @code{--with-system-poppler}@*Use a system version (0.18 or
newer) of @code{poppler} for Lua@TeX{} and Xe@TeX{}, and use
@file{pkg-config} to obtain the required flags.

@vindex --with-system-xpdf
@noindent @code{--with-system-xpdf}@*Use a system version (0.12 or better)
of @code{poppler} (and @file{pkg-config}) for pdf@TeX{} instead of
@code{xpdf} from the TL tree.  @xref{@code{--disable-largefile}}.

@node Variables for configure
@section Variables for configure

@cindex variables for @code{configure}
@cindex @code{configure} variables

The values for these variables can be specified as @code{configure}
arguments of the form @code{@var{VAR}=@var{value}}.  They can also be
defined in the environment, but that might not work for cross
compilations.

@vtable @code
@item CC
@itemx CXX
@itemx CPPFLAGS
And plenty more.  As usual with Autoconf, these variables specify the
name (or full path) of compilers, preprocessor flags, and similar.
@xref{Preset Output Variables,, autoconf, GNU Autoconf}.

@item CLISP
@pindex clisp
Name (or full path) of the @file{clisp} executable, used to build
@code{xindy}.

@item FT2_CONFIG
@itemx ICU_CONFIG
@itemx PKG_CONFIG
@pindex freetype-config
@pindex icu-config
@pindex libfreetype
@cindex ICU libraries
These specify the name (or path) for the @file{freetype-config},
@file{icu-config}, and @file{pkg-config} commands used to determine the
flags required for system versions of @file{libfreetype}, the ICU
libraries, or many other libraries.

@item KPSEWHICH
@pindex kpsewhich
Name (or path) of an installed @file{kpsewhich} binary, used by
@code{make check} to determine the location of, e.g.,
@file{cmbx10.tfm}.

@item MAKE
@itemx SED
And more. Name (or path) of the @code{make}, @code{sed}, and similar
programs; used at the top level and propagated to all subdirectories.

@item PERL
@itemx LATEX
@itemx PDFLATEX
Name (or full path) for the @file{perl}, @file{latex}, and @file{pdflatex}
commands used, e.g., to build the @code{xindy} documentation.

@end vtable


@node Cross compilation
@chapter Cross compilation

@cindex cross compilation
In a cross compilation a @dfn{build} system is used to create
binaries to be executed on a @dfn{host} system with different
hardware and/or operating system.

@cindex native cross compilation
In simple cases, the build system can execute binaries for the host
system.  This typically occurs for bi-arch systems where, e.g.,
@code{i386-linux} binaries can run on @code{x86_64-linux} systems and
@code{win32} binaries can run on @code{win64} systems.  Although
sometimes called ``native cross'', technically this is not cross
compilation at all.  In most such cases it suffices to specify
suitable compiler flags.  It might be useful to add the configure
option @code{--build=@var{host}} to get the correct canonical host
name, but note that this should @emph{not} be @code{--host=@var{host}}
(@pxref{Hosts and Cross-Compilation,,, autoconf, GNU Autoconf}).

In order to build, e.g., 32-bit binaries with @command{clang} on a 64-bit
OSX system one could use @* @ @ @ @code{./Build --build=i386-apple-darwin
CC='clang -arch i386'} @backslashchar{} @* @ @ @ @ @ @ @ @ @
@code{CXX='clang++ -arch i386' OBJCXX='clang++ -arch i386'}

@menu
* Cross configuring::           Configuring for cross compilation.
* Cross problems::              Cross compilation problems.
@end menu


@node Cross configuring
@section Cross configuring

@cindex cross compilation configuring
@cindex configuring, for cross compilation

@vindex --host=@var{host}
@vindex --build=@var{host}
In a standard cross compilation, binaries for the host system cannot
execute on the build system and it is necessary to specify the
configure options @code{--host=@var{host}} and
@code{--build=@var{build}} with two different values.

Building binaries requires suitable ``cross'' tools, e.g., compiler,
linker, and archiver, and perhaps a ``cross'' version of
@code{pkg-config} and similar to locate host system libraries.
Autoconf expects that these cross tools are given by their usual
variables or found under their usual name prefixed with
@code{@var{host}-}.  Here a list of such tools and corresponding
variables:

@example
@code{ar}                AR
@code{freetype-config}   FT2_CONFIG
@code{g++}               CXX
@code{gcc}               CC
@code{icu-config}        ICU_CONFIG
@code{objdump}           OBJDUMP
@code{pkg-config}        PKG_CONFIG
@code{ranlib}            RANLIB
@code{strip}             STRIP
@end example

@cindex @code{mingw32}
@noindent In order to, e.g., build @code{mingw32} binaries on
@code{x86_64-linux} with a cross compiler found as
@file{i386-pc-mingw32-gcc} one would specify

@example
--host=i386-pc-mingw32 --build=x86_64-linux-gnu
@end example

@noindent or perhaps

@example
--host=mingw32 --build=x86_64-linux CC=i386-pc-mingw32-gcc
@end example

@noindent but this latter, especially, might require adding @code{CXX} and others.

Configure arguments such as @code{CFLAGS=@dots{}} refer to the cross
compiler.  If necessary, you can specify compilers and flags for the
few auxiliary C and C++ programs required for the build process as
configure arguments

@vindex BUILDCC@r{,} BUILDCFLAGS@r{, @dots{}}
@example
BUILDCC=@dots{}
BUILDCPPFLAGS=@dots{}
BUILDCFLAGS=@dots{}
BUILDCXX=@dots{}
BUILDCXXFLAGS=@dots{}
BUILDLDFLAGS=@dots{}
@end example


@node Cross problems
@section Cross problems

@cindex cross compilation problems

The fact that binaries for the host system cannot be executed on the
build system causes some problems.

One problem is that configure tests using @code{AC_RUN_IFELSE} can
compile and link the test program but cannot execute it.  Such tests
should be avoided if possible and otherwise must supply a pessimistic
test result.

@pindex squeeze
@pindex web2c @r{program}
@cindex @code{freetype} cross compiling
@vindex CC_BUILD
Another problem arises if the build process must execute some
(auxiliary or installable) programs.  Auxiliary programs can be placed
into a subdirectory that is configured natively as is done for
@file{texk/web2c/web2c}, @file{texk/dvipsk/squeeze}, and
@file{texk/xdvik/squeeze}.  The module @file{libs/freetype2} uses the
value of @code{CC_BUILD}, @file{@var{build}-gcc}, @file{gcc}, or
@file{cc} as compiler for the auxiliary program.

@pindex txt2zlib
Building Lua@TeX{} (or LuaJIT@TeX{}) uses the auxiliary program
@file{txt2zlib} to create @file{pdflua.c} and, if necessary, update the
distributed version of that file.  In a cross compilation we simply use that
distributed file.

@cindex ICU cross compiling
The situation for installable programs needed by the build process is
somewhat different.  A quite expensive possibility, chosen for the ICU
libraries in module @file{libs/icu}, is to first compile natively for
the build system and in a second step to use these (uninstalled)
programs during the cross compilation.

@pindex tangle
@pindex ctangle
@pindex otangle
@pindex tie
This approach would also be possible for the tools such as
@file{tangle} used in the module @file{texk/web2c} to build the WEB
programs, but that would require first building a native
@code{kpathsea} library.  To avoid this complication, cross
compilation of the WEB or CWEB programs requires sufficiently recent
installed versions of @file{tangle}, @file{ctangle}, @file{otangle},
and @file{tie}.

@cindex @code{xindy} cross compiling impossible
Building @code{xindy} requires running the host system @file{clisp}
binary, thus cross compilation is not possible.


@node Coding conventions
@chapter Coding conventions

@cindex coding conventions
@cindex conventions, coding

Ideally, building all of @TL{} with @code{--enable-compiler-warnings=max}
should produce no (GCC) compiler warnings at all.  In spite of
considerable efforts into that direction we are still far from that goal and
there are reasons that we may never fully reach it.  Below are some rules
about declarations of functions or variables and the use of @code{const}. 
These rules should be applied to all parts of the @TL{} tree, except some of
those maintained independently.

@menu
* Declarations and definitions::
* Const::
@end menu


@node Declarations and definitions
@section Declarations and definitions

@cindex declarations and definitions, in source code
@cindex source code declarations
@cindex ANSI C
@cindex C, ANSI, required
@cindex C99, avoided

@subsubheading C standards

The @TL{} build system no longer supports pre-ANSI C compilers.  Thus
all function prototypes and definitions must conform to the ANSI C
standard (including @code{void} in the declaration of C functions with
no parameters).  On the other hand, TL is built for a wide variety of
systems, not all of which support the C99 standard.  Therefore using
C99 features should be avoided if that can easily be done.  In
particular C code must not contain declarations after statements or
C++-style comments.

@pindex chktex
@findex stpcpy
If some C99 (or later) constructs must be used, the module should
verify that they are available and otherwise provide an alternative.
For example, the module @file{texk/chktex} uses the C99 function
@code{stpcpy()} that may or may not be available on a particular
system.  It uses @code{AC_CHECK_DECLS([stpcpy])} in
@file{configure.ac} to test this, and provides the perhaps slightly
less efficient alternative

@example
#if !(defined HAVE_DECL_STPCPY && HAVE_DECL_STPCPY)
#static inline char *stpcpy(char *dest, const char *src)
@{
  return strcpy(dest, src) + strlen(src);
@}
#endif
@end example

@noindent in the file @file{Utility.h}.


@subsubheading Static functions

@cindex @code{static} functions
Functions used in only one file should be declared @code{static}; they
require no prototype except as forward declaration.

@subsubheading Extern functions

@cindex @code{extern} functions
Functions not declared @code{static}, usually because they are used in
several files, require an (@code{extern}) prototype in exactly one
header file, which is included in the file defining the function and
in all files using that function---this is the only way to guarantee
consistency between definition and use.  There should be no
@code{extern} declarations sprinkled throughout the C code (with or
without comments as to where that function is defined).

@subsubheading Variable declarations

@cindex variable declarations, in source code
The declaration of global variables follows analogous rules: they are
either declared @code{static} if used in only one file or declared
@code{extern} in exactly one header and instantiated in exactly one
file.

@node Const
@section Const

@cindex @code{const}

The @code{const} feature of C is valuable, but easy to mis-use.

@subsubheading Function parameters

Ideally, a function parameter not modified by the function should be
declared as @code{const}.  This is important in particular for strings
(@code{char*}) because the actual arguments are often string literals.
It is perfectly legitimate and safe to use a type @code{char*} value
for a type @code{const char*} variable (in an assignment, as
initializer, as function argument, or as return value).  It is equally
safe to use a type @code{char**} value for a type @code{const
char*const*} variable, but not for a type @code{const char**} variable
since that might cause modification of a quantity supposed to be
constant.

@cindex X11 headers, and @code{const}
@cindex @code{libfreetype}, and @code{const}
Getting all @code{const} qualifiers right can get quite involved but
can almost always be done.  There are only a couple notable
exceptions: the X11 headers are full of declarations that ought to use
@code{const} but do not, and the same is true to some extent for
@file{libfreetype} (but, thankfully, not for @code{zlib} nowadays).

@subsubheading What must be avoided with @code{const}

@cindex warning, discards qualifiers
@cindex discards qualifiers warning
The GCC compiler warnings ``assignment discards qualifiers@dots{}''
and analogous warnings for ``initialization'', ``passing arg'', or
``return'' must be strenously avoided in our own code.  The only
exception is when they are caused by X11 headers or macros or other
third party code.

@subsubheading What should be avoided with @code{const}

@cindex type cast, avoiding
A type cast, e.g., from @code{const char*} to @code{char*} does not
solve any problems; depending on warning options, it may only hide
them.  Therefore such casts should be avoided whenever possible and
otherwise must be carefully analyzed to make sure that they cannot
cause the modification of quantities supposed to be constant.

@c made from pod doc.
@include tlbuild-incl/install-tl.texi
@include tlbuild-incl/tlmgr.texi

@node Index
@unnumbered Index

@printindex cp

@bye
