dpkg-cross(1)
Name
dpkg-cross - manage libraries for cross compiling
Copyright and Licence
Copyright (C) 1997-2000 Roman Hodek <roman@hodek.net>
Copyright (C) 2000-2002 Colin Watson <cjwatson@debian.org>
Copyright (C) 2002-2004 David Schleef <ds@schleef.org>
Copyright (C) 2004 Nikita Youshchenko <yoush@cs.msu.su>
Copyright (C) 2004 Raphael Bossek <bossekr@debian.org>
Copyright (c) 2007-2011 Neil Williams <codehelp@debian.org>
Copyright (c) 2011 Wookey <wookey@debian.org>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
SYNOPSIS
dpkg-cross [OPTIONS] [--install|-i] <files...>
dpkg-cross [OPTIONS] [--build|-b] <files...>
dpkg-cross [OPTIONS] [--remove|--purge|-r] <packages...>
dpkg-cross [OPTIONS] [--status|-s] <packages...>
dpkg-cross [OPTIONS] [--list|-l] <packages...>
dpkg-cross [OPTIONS] [--list-files|-L] <packages...>
dpkg-cross [OPTIONS] [--query|-Q] <pkgpath>
dpkg-cross [OPTIONS] [--update|-u] <pkgpath>
OPTIONS: [ -v | --verbose ] [ -q | --quiet ]
{ [ -a | --arch ] architecture } { [ -X | --exclude ] PACKAGE }
[ -A | --convert-anyway ] [ -M | --convert-multiarch ] [ -k | --keep-temp ]
DESCRIPTION
dpkg-cross is a tool to install and manage libraries and header files for cross compiling. dpkg-cross converts native Debian packages for the target architecture to cross compiling support packages that can be installed on any architecture, but in different paths to avoid conflicts. It then calls dpkg to install the converted package. The conversion step alone can be done with the --build option. Other options are wrappers around corresponding dpkg functionality. dpkg-cross is intended to make it easier for you to keep your cross compiling libraries up-to-date, as it works directly on Debian packages. It saves you copying the libs and headers from a machine with your target architecture, or extracting them via dpkg-deb --fsys-tarfile. dpkg-cross also collects and install the .shlibs files in -dev packages, which are needed by dpkg-shlibdeps.
CMAKE
CMake cross-building support is experimental!
CMake requires a little support from dpkg-cross to cross-build. The
included cmake support file is an example for Linux kernels. Use:
rm CMakeCache.txt
cmake -DCMAKE_TOOLCHAIN_FILE=/etc/dpkg-cross/cmake/CMakeCross.txt
The main changes involve setting PKG_CONFIG_LIBDIR within CMake an
setting the include directories to locate the cross libraries installed
by dpkg-cross e.g.
#Make pkg-config look in the right place
SET(ENV{PKG_CONFIG_LIBDIR} ${CMAKE_FIND_ROOT_PATH}/lib/pkgconfig/)
ELSE (CMAKE_CROSSCOMPILING)
Packages using cmake may need some tweaks to debian/rules, e.g.
ifneq ($(DEB_HOST_GNU_TYPE),$(DEB_BUILD_GNU_TYPE))
export CC=$(DEB_HOST_GNU_TYPE)-gcc
export CXX=$(DEB_HOST_GNU_TYPE)-g++
export CMAKE_TOOLCHAIN_FILE=/etc/dpkg-cross/cmake/CMakeCross.txt
else
export CC=gcc
export CXX=g++
endif
OPTIONS
dpkg-cross follows the usual GNU command line syntax, with long options
starting with two dashes ('-').
-h|--help
Show summary of options.
-v|--verbose
Be more verbose.
-q|--quiet
Be more quiet.
-a|--arch architecture
Install for architecture architecture.
-i|--install
Install Debian packages (.deb) named on the command line. Only files in
the directories /lib, /usr/lib and /usr/include are extracted, since
only they can be relevant for cross compiling. In the lib directories,
also no subdirectories are extracted.
-A|--convert-anyway
Convert Debian package even if it does not provide any files useful for
cross-compile environment.
-M|--convert-multiarch
Convert package even if it is a multiarch package. If the package is
not a multiarch package, processing continues as normal.
-X|--exclude PACKAGE
Removes the specified package from the dependencies of the current
package. Typically used to drop dependencies on packages that are not
required within a cross-build environment, e.g. packages containing
only executables or architecture independent files.
dpkg-cross can only check the current package and information about a
dependency is not available (for that, use xapt). By default, dpkg-
cross converts all dependencies to specify the cross version of the
dependency package.
If you know that a particular dependency should not be converted (it
provides no useful files or is architecture independent), that
dependency can be excluded and dpkg-cross will remove that package from
the dependency information of the cross package. -X has replaced the
use of keepdeps and removedeps in /etc/dpkg-cross/cross-compile.
-X|--exclude PACKAGE needs to be repeated for each package to be
excluded.
-k|--keep-temp
Keep the built and installed package instead of deleting it. Requires
--install.
-b|--build
Just build the converted Debian package, but do not install it with
dpkg.
-r|--remove
Remove the cross compiling packages named on the command line.
-s|--status
Print status of the named packages.
-l|--list
Print short version of status of named packages or package name
patterns.
-L|--list-files
List files belonging to the named packages.
-u|--update
Update current cross-installation with Debian packages found in/under
the paths given as arguments. Will check all packages there if they are
installed already as cross-compiling packages and if they are really
updates. Those packages will be installed as with -i.
-Q|--query
Much like --update, but just prints available update packages and does
not install them.
FILES
/etc/dpkg-cross/cross-compile defines the default_arch for dpkg-cross:
The default architecture for dpkg-cross is normally set by debconf. To
change the system-wide value, use:
$ sudo dpkg-reconfigure dpkg-cross
Alternatively, the default can be overridden on a per-user basis using
the optional file in $HOME/.dpkg-cross/
Conversion process
There is no safe way for dpkg-cross to mangle certain files in -dev packages, particularly files in /usr/share or to determine precisely which of these files could be parsed and which cannot. Special cases do not help - dpkg-cross already has too many of those. It is not safe to leave files in the package nor is it safe to move files into arbitrary locations when there is no reliable and standardised way to determine the usefulness of a particular kind of file. Package specific config scripts cannot be supported and even build-system specific ones are not necessarily going to work without a lot of ongoing maintenance. Therefore, "dpkg-cross" is very restrictive on which files are retained in the -cross package. Files to be converted All files in /usr/include/* Also /usr/src and /usr/lib are searched for includes - files with .h, .hh, .hpp extensions (case insensitive). Library files - *.so* and *.a and *.o files from /lib and /usr/lib (and all the multilib eqivalents (lib64, lib32, libo32, libhf, libx32 etc). Other library files are not copied. *.la files in library directories are also copied, and library and paths are modified there. Same for /usr/lib/pkgconfig/*.pc files. Symlinks are copied (and modified appropriately) if their destination is copied. Also, symlinks to non-existing shared libraries are copied (this is common case for libdevel packages) Directories are created only to hold some files or symlinks. No empty directories are copied.
Multiarch behaviour
By default <dpkg-cross> does nothing with packages from Debian which already support Multi-Arch - the package is simply copied to the current work directory, if it does not already exist. Any package containing a Multi-Arch: field in DEBIAN/control is skipped in this manner. --convert-multiarch can be specified to instead force the generation of a -<arch>-cross package with the files moved into the conventional dpkg-cross locations. The Multiarch spec ensures that multiarch packages will only be available from Debian mirrors once dpkg itself is capable of installing the packages and installing a Multiarch package means being able to install a 32bit multiarch package alongside a 64bit multiarch package. Installing an armel multiarch package alongside an x86 multiarch package is no different to 32bit vs 64bit. (What changes is how the multiarch package itself handles the header files and pkg-config files.)
Opportunity
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
Free Books
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Education
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.
