This document contains instructions on how to cross-build the FreeType
library on Unix systems, for example, building binaries for Linux/MIPS
on FreeBSD/i386. Before reading this document, please consult the
file `INSTALL.UNIX' for required tools and the basic self-building
procedure.
1. Required Tools
-----------------
For self-building the FreeType library on a Unix system, GNU Make
3.81 or newer is required. `INSTALL.UNIX' contains hints how to
check the installed `make'.
The GNU C compiler to cross-build the target system is required.
Currently, using a non-GNU cross compiler is untested. The cross
compiler is expected to be installed with a system prefix. For
example, if your building system is FreeBSD/i386 and the target
system is Linux/MIPS, the cross compiler should be installed with
the name `mips-ip22-linuxelf-gcc'.
A C compiler for a self-build is required also, to build a tool
(`apinames') that is executed during the build procedure. Non-GNU
self compilers are acceptable, but such a setup is untested.
2. Configuration
----------------
2.1. Building and target system
To configure a cross-build, the options `--host=<system>' and
`--build=<system>' must be passed to the `configure' script.
For example, if your build system is FreeBSD/i386 and the target
system is Linux/MIPS, say
./configure \
--build=i386-unknown-freebsd \
--host=mips-ip22-linuxelf \
[other options]
It should be noted that `--host=<system>' specifies the system
where the built binaries will be executed, not the system where
the build actually happens. Older versions of GNU autoconf use
the option pair `--host=' and `--target='. This is broken and
doesn't work. Similarly, an explicit CC specification like
env CC=mips-ip22-linux-gcc ./configure # BAD
or
env CC=/usr/local/mips-ip22-linux/bin/gcc ./configure # BAD
doesn't work either; such a configuration confuses the
`configure' script while trying to find the cross and native C
compilers.
2.2. The prefix to install FreeType2
Setting `--prefix=<prefix>' properly is important. The prefix
to install FreeType2 is written into the `freetype-config'
script and `freetype2.pc' configuration file.
If the built FreeType 2 library is used as a part of the
cross-building system, the prefix is expected to be different
from the self-building system. For example, a configuration
with `--prefix=/usr/local' installs binaries into the
system-wide `/usr/local' directory, which then can't be executed
due to the incorrect architecture. This causes confusion in
configuration of all applications that use FreeType2. Instead,
use a prefix to install the cross-build into a separate system
tree, for example, `--prefix=/usr/local/mips-ip22-linux/'.
On the other hand, if the built FreeType 2 library is used as a
part of the target system, the prefix to install should reflect
the file system structure of the target system.
2.3. Library dependencies
FreeType normally depends on external libraries like `libpng' or
`libharfbuzz'. The easiest case is to deactivate all such
dependencies using the `--without-XXX' configuration options.
However, if you want to use those libraries, you should ensure
that they are available both on the target system and as
(cross-compiled) libraries on the build system.
FreeType uses `pkg-config' to find most of the libraries; the
other libraries it links to are expected in the standard system
directories. Since the default pkg-config's meta-information
files (like `harfbuzz.pc') of the build platform don't work, use
one of the two possible solutions below.
o Use pkg-config's meta-information files that are adjusted to
cross-compile and cross-link with the target platform's
libraries. Make sure those files are found before the build
system's default files. Example:
./configure \
--build=i386-unknown-freebsd \
--host=mips-ip22-linuxelf \
PKG_CONFIG_LIBDIR="/usr/local/mips-ip22-linux/lib/pkgconfig" \
[other options]
See the manpage of `pkg-config' for more details.
o Set variables like LIBPNG_LIBS as additional options to the
`configure' script, overriding the values `pkg-config' would
provide. `configure --help' shows the available environment
variables. Example:
./configure \
--build=i386-unknown-freebsd \
--host=mips-ip22-linuxelf \
LIBPNG_CFLAGS="-I/usr/local/mips-ip22-linux/include" \
LIBPNG_LIBS="-L/usr/local/mips-ip22-linux/lib -lpng12" \
[other options]
3. Building command
-------------------
If the configuration finishes successfully, invoking GNU make
builds FreeType2. Just say
make
or
gmake
depending on the name the GNU make binary actually has.
4. Installation
---------------
Saying
make install
as usual to install FreeType2 into the directory tree specified by
the argument of the `--prefix' option.
As noted in section 2.2, FreeType2 is sometimes configured to be
installed into the system directory of the target system, and
should not be installed in the cross-building system. In such
cases, the make variable `DESTDIR' is useful to change the root
directory in the installation. For example, after
make DESTDIR=/mnt/target_system_root/ install
the built FreeType2 library files are installed into the directory
`/mnt/target_system_root/<prefix_in_configure>/lib'.
5. TODO
-------
Cross building between Cygwin (or MSys) and Unix must be tested.
----------------------------------------------------------------------
Copyright (C) 2006-2022 by
suzuki toshiya, David Turner, Robert Wilhelm, and Werner Lemberg.
This file is part of the FreeType project, and may only be used,
modified, and distributed under the terms of the FreeType project
license, LICENSE.TXT. By continuing to use, modify, or distribute
this file you indicate that you have read the license and understand
and accept it fully.
--- end of INSTALL.CROSS ---
