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[emacs.git] / nt / INSTALL

                    Building and Installing Emacs on MS-Windows
                          using the MSYS and MinGW tools

  Copyright (C) 2013-2014 Free Software Foundation, Inc.
  See the end of the file for license conditions.

The MSYS/MinGW build described here is supported on versions of
Windows starting with Windows 2000 and newer.  Windows 9X are not
supported (but the Emacs binary produced by this build will run on
Windows 9X as well).

  Do not use this recipe with Cygwin.  For building on Cygwin, use the
  normal installation instructions, ../INSTALL.

* For the brave (a.k.a. "impatient"):

  For those who have a working MSYS/MinGW development environment and
  are comfortable with running Posix configure scripts, here are the
  concise instructions for configuring and building the native Windows
  binary of Emacs with these tools:

  0. Start the MSYS Bash window.  Everything else below is done from
     that window's Bash prompt.

  0a. If you are building from the development trunk (as opposed to a
      release tarball), produce the configure script, by typing from
      the top-level Emacs source directory:

      ./autogen.sh

  1. If you want to build Emacs outside of the source tree
     (recommended), create the build directory and chdir there.

  2. Invoke the configure script:

      - If you are building outside the source tree:

        /PATH/TO/EMACS/SOURCE/TREE/configure --prefix=PREFIX ...

      - If you are building in-place, i.e. inside the source tree:

        ./configure --prefix=PREFIX ...

     It is always preferable to use --prefix to configure Emacs for
     some specific location of its installed tree; the default
     /usr/local is not suitable for Windows (see the detailed
     instructions for the reasons).  The prefix must be absolute.

     You can pass other options to the configure script.  Here's a
     typical example (for an in-place debug build):

       CFLAGS='-O0 -g3' ./configure --prefix=/d/usr/emacs --enable-checking='yes,glyphs'

  3. After the configure script finishes, it should display the
     resulting configuration.  After that, type

       make

     Use "make -j N" if your MSYS Make supports parallel execution;
     the build will take significantly less time in that case.  Here N
     is the number of simultaneous parallel jobs; use the number of
     the cores on your system.

  4. Install the produced binaries:

       make install

     If you want the installation tree to go to a place that is
     different from the one specified by --prefix, say

       make install prefix=/where/ever/you/want

  That's it!

  If these short instructions somehow fail, read the rest of this
  file.

* Installing MinGW and MSYS

  Make sure you carefully read the following two sections in their
  entirety and install/configure the various packages as instructed.
  A correct installation makes all the rest almost trivial; a botched
  installation will likely make you miserable for quite some time.

  There are two alternatives to installing MinGW + MSYS: using the GUI
  installer, called mingw-get, provided by the MinGW project, or
  manual installation.  The next two sections describe each one of
  these.

** Installing MinGW and MSYS using mingw-get

  A nice installer, called mingw-get, is available for those who don't
  like to mess with manual installations.  You can download it from
  here:

    https://sourceforge.net/projects/mingw/files/Installer/mingw-get/

  (This installer only supports packages downloaded from the MinGW
  site; for the rest you will still need the manual method.)

  After installing mingw-get, invoke it to install the packages that
  are already selected by default on the "Select Components" screen of
  its wizard.

  After that, use "mingw-get install PACKAGE" to install the following
  additional packages:

   . msys-base
   . mingw-developer-toolkit

  (We recommend that you refrain from installing the MSYS Texinfo
  package, which is part of msys-base, because it might produce mixed
  EOL format when installing Info files.  Instead, install the MinGW
  port of Texinfo, see the ezwinports URL below.  To uninstall the
  MSYS Texinfo, after installing it as part of msys-base, invoke the
  command "mingw-get remove msys-texinfo".)

  At this point, you should be ready to configure and build Emacs in
  its basic configuration.  Skip to the "Generating the configure
  script" section for the build instructions.  If you want to build it
  with image support and other optional libraries, read about the
  optional libraries near the end of this document, before you start
  the build.  Also, consider installing additional MinGW packages that
  are required/recommended, especially if you are building from the
  repository, as described in the next section.

** Installing MinGW and MSYS manually

*** MinGW

  You will need to install the MinGW port of GCC and Binutils, and the
  MinGW runtime and Windows API distributions, to compile Emacs.  You
  can find these on the MinGW download/Base page:

    https://sourceforge.net/projects/mingw/files/MinGW/Base/

  In general, install the latest stable versions of the following
  MinGW packages from that page: gcc, binutils, mingw-rt, w32api.  You
  only need the 'bin' and the 'dll' tarballs of each of the above.

  MinGW packages are distributed as .tar.lzma compressed archives.  To
  install the packages manually, we recommend to use the Windows port
  of the 'bsdtar' program to unpack the tarballs.  'bsdtar' is
  available as part of the 'libarchive' package from here:

    http://sourceforge.net/projects/ezwinports/files/

  The recommended place to install these packages is a single tree
  starting from some directory on a drive other than the system drive
  C:.  A typical example would be D:\usr, with D:\usr\bin holding the
  binaries and DLLs (should be added to your Path environment
  variable), D:\usr\include holding the include files, D:\usr\lib
  holding the static and import libraries, D:\usr\share holding docs,
  message catalogs, and package-specific subdirectories, etc.

  Having all the headers and libraries in a single place will greatly
  reduce the number of -I and -L flags you will have to pass to the
  configure script (see below), as these files will be right where the
  compiler expects them.

  We specifically do NOT recommend installing packages below
  "C:\Program Files" or "C:\Program Files (x86)".  These directories
  are protected on versions of Windows from Vista and on, and you will
  have difficulties updating and maintaining your installation later,
  due to UAC elevation prompts, file virtualization, etc.  You *have*
  been warned!

  Additional MinGW packages are required/recommended, especially if
  you are building from the repository:

   . Texinfo (needed to produce the Info manuals when building from
     the repository, and for "make install")

     Available from http://sourceforge.net/projects/ezwinports/files/.

   . gzip (needed to compress files during "make install")

     Available from http://gnuwin32.sourceforge.net/packages/gzip.htm.

   . pkg-config (needed for building with some optional libraries,
     such as GnuTLS and libxml2)

     Available from http://www.gtk.org/download/win32.php

  Each package might list other packages as prerequisites on its
  download page (under "Runtime requirements"); download those as
  well.  (Using the mingw-get installer will fetch those prerequisites
  automatically for you.)  A missing prerequisite will manifest itself
  by the program failing to run and presenting a pop-up dialog that
  states the missing or incompatible DLL; be sure to find and install
  these missing DLLs.

  Once you think you have MinGW installed, test the installation by
  building a trivial "hello, world!" program, and make sure that it
  builds without any error messages and the binary works when run.

*** MSYS

  You will need a reasonably full MSYS installation.  MSYS is an
  environment needed to run the Posix configure scripts and the
  resulting Makefile's, in order to produce native Windows binaries
  using the MinGW compiler and runtime libraries.  Here's the list of
  MSYS packages that are required:

   . All the packages from the MSYS Base distribution, listed here:

     https://sourceforge.net/projects/mingw/files/MSYS/Base/

   . Additional packages listed below, from the MSYS Extension
     distribution here:

     https://sourceforge.net/projects/mingw/files/MSYS/Extension/

      - flex
      - bison
      - m4
      - perl
      - mktemp

     These should only be needed if you intend to build development
     versions of Emacs from the repository.

   . Additional packages (needed only if building from the
     repository): Automake and Autoconf.  They are available from
     here:

       http://sourceforge.net/projects/ezwinports/files/automake-1.11.6-msys-bin.zip/download
       http://sourceforge.net/projects/ezwinports/files/autoconf-2.65-msys-bin.zip/download

  MSYS packages are distributed as .tar.lzma compressed archives.  To
  install the packages manually, we recommend to use the Windows port
  of the 'bsdtar' program, already mentioned above.

  MSYS packages should be installed in a separate tree from MinGW.
  For example, use D:\MSYS or D:\usr\MSYS as the top-level directory
  from which you unpack all of the MSYS packages.

  If/when you are confident in your MinGW/MSYS installation, and want
  to speed up the builds, we recommend installing a pre-release
  version of Make from here:

     https://sourceforge.net/projects/mingwbuilds/files/external-binary-packages/

  These are snapshot builds of many packages, but you only need
  make.exe from there.  The advantage of this make.exe is that it
  supports parallel builds, so you can use "make -j N" to considerably
  speed up your builds.

  Several users reported that MSYS 1.0.18 causes Make to hang in
  parallel builds.  If you bump into this, we suggest to downgrade to
  MSYS 1.0.17, which doesn't have that problem.

  For each of these packages, install the 'bin' and 'dll' tarballs of
  their latest stable releases.  If there's an 'ext' tarball (e.g.,
  msysCORE and Coreutils have it), download and install those as well.

  Each package might list other packages as prerequisites on its
  download page (under "Runtime requirements"); download those as
  well.  (Using the mingw-get installer will fetch those prerequisites
  automatically for you.)  A missing prerequisite will manifest itself
  by the program failing to run and presenting a pop-up dialog that
  states the missing or incompatible DLL; be sure to find and install
  these missing DLLs.

  Do NOT add the MSYS bin directory to your Windows Path!  Only the
  MinGW bin directory should be on Path.  When you install MSYS, it
  creates a shortcut on your desktop that invokes the MSYS Bash shell
  in a Command Prompt window; that shell is already set up so that the
  MSYS bin directory is on PATH ahead of any other directory.  Thus,
  Bash will find MSYS executables first, which is exactly what you
  need.

* Starting the MSYS Bash shell

  For most reliable and predictable results, we recommend to start
  Bash by clicking the "MSYS" icon on your desktop.  That icon is
  created when you install MSYS, and using it is the official way of
  running the MSYS tools.

  For other methods of starting the shell, make sure Bash is invoked
  with the "--login" command-line switch.

  When the shell window opens and you get the shell prompt, change to
  the directory where you intend to build Emacs.

  At this point, you are ready to build Emacs in its basic
  configuration.  If you want to build it with image support and other
  optional libraries, read about that near the end of this document.

* Generating the configure script

  If you are building a release or pretest tarball, skip this section,
  because the configure script is already present in the tarball.

  To build a development snapshot from the Emacs repository,
  you will first need to generate the configure script and a few other
  auto-generated files.

  To generate the configure script, type this at the MSYS Bash prompt
  from the top-level directory of the Emacs source tree:

     ./autogen.sh

  If successful, this command should produce the following output:

     $ ./autogen.sh
     Checking whether you have the necessary tools...
     (Read INSTALL.REPO for more details on building Emacs)

     Checking for autoconf (need at least version 2.65)...
     ok
     Checking for automake (need at least version 1.11)...
     ok
     Your system has the required tools, running autoreconf...
     You can now run `./configure'.

* Configuring Emacs for MinGW:

  Now it's time to run the configure script.  You can do that either
  from a separate build directory that is outside of the Emacs source
  tree (recommended), or from inside the source tree.  The former is
  recommended because it allows you to have several different builds,
  e.g., an optimized build and an unoptimized one, of the same
  revision of the source tree; the source tree will be left in its
  pristine state, without any build products.

  You invoke the configure script like this:

     /PATH/TO/EMACS/SOURCE/TREE/configure --prefix=PREFIX ...

  or, if you are building in-place, i.e. inside the source tree:

     ./configure --prefix=PREFIX ...

  Here PREFIX is the place where you eventually want to install Emacs
  once built, e.g. /d/usr.  We recommend to always use --prefix when
  building Emacs on Windows, because the default '/usr/local' is not
  appropriate for Windows: it will be mapped by MSYS to something like
  C:\MSYS\local, and it will defeat the purpose of PREFIX, which is to
  install programs in a single coherent tree resembling Posix systems.
  Such a single-tree installation makes sure all the other programs
  and packages ported from GNU or Unix systems will work seamlessly
  together.  Where exactly is the root of that tree on your system is
  something only you, the user who builds Emacs, can know, and the
  Emacs build process cannot guess, because usually there's no
  '/usr/local' directory on any drive on Windows systems.

  Do NOT use Windows-style x:/foo/bar file names on the configure
  script command line; use the MSYS-style /x/foo/bar instead.  Using
  Windows-style file names was reported to cause subtle and hard to
  figure out problems during the build.  This applies both to the
  command switches, such as --prefix=, and to the absolute file name
  of 'configure', if you are building outside of the source tree.

  You can pass additional options to the configure script, for the
  full list type

     ./configure --help

  As explained in the help text, you may need to tell the script what
  are the optional flags to invoke the compiler.  This is needed if
  some of your headers and libraries, e.g., those belonging to
  optional image libraries, are installed in places where the compiler
  normally doesn't look for them.  (Remember that advice above to
  avoid such situations? here's is where you will start paying for
  disregarding that recommendation.)  For example, if you have libpng
  headers in C:\emacs\libs\libpng-1.2.37-lib\include and jpeg library
  headers in C:\emacs\libs\jpeg-6b-4-lib\include, you will need to say
  something like this:

    CPPFLAGS='-I/c/emacs/libs/libpng-1.2.37-lib/include -I/c/emacs/libs/jpeg-6b-4-lib/include' ./configure --prefix=PREFIX

  which is quite a mouth-full, especially if you have more directories
  to specify...  Perhaps you may wish to revisit your installation
  decisions now.

  If you have a global site-lisp directory from previous Emacs
  installation, and you want Emacs to continue using it, specify it
  via the --enable-locallisppath switch to 'configure', like this:

   ./configure --prefix=PREFIX --enable-locallisppath="/d/usr/share/emacs/VERSION/site-lisp:/d/wherever/site-lisp"

  Use the normal MSYS /d/foo/bar style to specify directories by their
  absolute file names.

  A few frequently used options are needed when you want to produce an
  unoptimized binary with runtime checks enabled:

     CFLAGS='-O0 -g3' ./configure --prefix=PREFIX --enable-checking='yes,glyphs'

  Once invoked, the configure script will run for some time, and, if
  successful, will eventually produce a summary of the configuration
  similar to this:

     Configured for `i686-pc-mingw32'.

       Where should the build process find the source code?    /path/to/emacs/sources
       What compiler should emacs be built with?               gcc  -std=gnu99 -O0 -g3
       Should Emacs use the GNU version of malloc?             yes
       Should Emacs use a relocating allocator for buffers?    yes
       Should Emacs use mmap(2) for buffer allocation?         no
       What window system should Emacs use?                    w32
       What toolkit should Emacs use?                          none
       Where do we find X Windows header files?                NONE
       Where do we find X Windows libraries?                   NONE
       Does Emacs use -lXaw3d?                                 no
       Does Emacs use -lXpm?                                   yes
       Does Emacs use -ljpeg?                                  yes
       Does Emacs use -ltiff?                                  yes
       Does Emacs use a gif library?                           yes
       Does Emacs use -lpng?                                   yes
       Does Emacs use -lrsvg-2?                                no
       Does Emacs use imagemagick?                             no
       Does Emacs use -lgpm?                                   no
       Does Emacs use -ldbus?                                  no
       Does Emacs use -lgconf?                                 no
       Does Emacs use GSettings?                               no
       Does Emacs use -lselinux?                               no
       Does Emacs use -lgnutls?                                yes
       Does Emacs use -lxml2?                                  yes
       Does Emacs use -lfreetype?                              no
       Does Emacs use -lm17n-flt?                              no
       Does Emacs use -lotf?                                   no
       Does Emacs use -lxft?                                   no
       Does Emacs use toolkit scroll bars?                     yes

  You are almost there, hang on.

  If the output is significantly different, or if configure finishes
  prematurely and displays some error message, you should examine the
  configuration log in config.log and find the reason for the failure.

  Once you succeeded in configuring Emacs, and just want to rebuild it
  after updating your local repository from the main repository, you
  don't need to re-run the configure script manually, unless you want
  to change the configure-time options.  Just typing "make" will
  re-run configure if necessary with the exact same options you
  specified originally, and then go on to invoking Make, described
  below.

* Running Make.

  This is simple: just type "make" and sit back, watching the fun.

  If you  installed a snapshot build  of Make, the build  will be much
  faster if  you type "make  -j N" instead, where  N is the  number of
  independent processing  units on your  machine.  E.g., on a  core i7
  system try using  N of 6 or  even 8.  (If this hangs,  see the notes
  above about downgrading to MSYS 1.0.17.)

  When Make finishes, you can install the produced binaries:

    make install

  or, if you want the installed tree to go in a place different from
  the configured one, type

    make install prefix=WHEREVER

  Congrats!  You have built and installed your own Emacs!

* Make targets

  The following make targets may be used by users building the source
  distribution, or users who have checked out of the repository after
  an initial bootstrapping.

  make
  Builds Emacs from the available sources and pre-compiled lisp files.

  make install
  Installs the built programs and the auxiliary files.

  make clean
  Removes object and executable files produced by the build process in
  the current configuration.  After "make clean", you can rebuild with
  the same configuration using make.  useful when you want to be sure
  that all of the products are built from coherent sources.

  make distclean
  In addition to the files removed by make clean, this also removes
  Makefiles and other generated files to get back to the state of a
  freshly unpacked source distribution.  After make distclean, it is
  necessary to run the configure script followed by "make", in order
  to rebuild.

  The following targets are intended only for use with the repository
  sources.

  make bootstrap
  Removes all the auto-generated files and all the *.elc byte-compiled
  files, and builds Emacs from scratch.  Useful when some change in
  basic Emacs functionality makes byte compilation of updated files
  fail.

  make maintainer-clean
  Removes everything that can be recreated, including compiled Lisp
  files, to get back to the state of a fresh repository tree.  After make
  maintainer-clean, it is necessary to run configure and "make" or
  "make bootstrap" to rebuild.  Occasionally it may be necessary to
  run this target after an update.

* Optional image library support

  In addition to its "native" image formats (pbm and xbm), Emacs can
  handle other image types: xpm, tiff, gif, png, jpeg and experimental
  support for svg.

  To build Emacs with support for them, the corresponding headers must
  be in the include path and libraries should be where the linker
  looks for them, when the configure script is run.  If needed, this
  can be set up using the CPPFLAGS and CFLAGS variable specified on
  the configure command line.  The configure script will report
  whether it was able to detect the headers and libraries.  If the
  results of this testing appear to be incorrect, please look for
  details in the file config.log: it will show the failed test
  programs and compiler error messages that should explain what is
  wrong.  (Usually, any such failures happen because some headers are
  missing due to bad packaging of the image support libraries.)

  Note that any file path passed to the compiler or linker must use
  forward slashes, or double each backslash, as that is how Bash
  works.

  If the configure script finds the necessary headers and libraries,
  but they are for some reason incompatible, or if you want to omit
  support for some image library that is installed on your system for
  some other reason, use the --without-PACKAGE option to configure,
  such as --without-gif to omit GIF, --without-tiff to omit TIFF, etc.
  Passing the --help option to the configure script displays all of
  the supported --without-PACKAGE options.

  To use the external image support, the DLLs implementing the
  functionality must be found when Emacs first needs them, either on the
  PATH, or in the same directory as emacs.exe.  Failure to find a
  library is not an error; the associated image format will simply be
  unavailable.  Note that once Emacs has determined that a library can
  not be found, there's no way to force it to try again, other than
  restarting.  See the variable `dynamic-library-alist' to configure the
  expected names of the libraries.

  Some image libraries have dependencies on one another, or on zlib.
  For example, tiff support depends on the jpeg library.  If you did not
  compile the libraries yourself, you must make sure that any dependency
  is in the PATH or otherwise accessible and that the binaries are
  compatible (for example, that they were built with the same compiler).

  For PNG images, we recommend to use versions 1.4.x and later of
  libpng, because previous versions had security issues.  You can find
  precompiled libraries and headers on the GTK download page for
  Windows (http://www.gtk.org/download/win32.php for 32-bit builds and
  http://www.gtk.org/download/win64.php for 64-bit builds).  The
  ezwinports site, http://sourceforge.net/projects/ezwinports/files/
  also offers PNG (as well as other image libraries), which are
  usually newer.

  Versions 1.4.0 and later of libpng are binary incompatible with
  earlier versions, so Emacs will only look for libpng libraries which
  are compatible with the version it was compiled against.  That
  version is given by the value of the Lisp variable `libpng-version';
  e.g., 10403 means version 1.4.3.  The variable `dynamic-library-alist'
  is automatically set to name only those DLL names that are known to
  be compatible with the version given by `libpng-version'.  If PNG
  support does not work for you even though you have the support DLL
  installed, check the name of the installed DLL against
  `dynamic-library-alist' and the value of `libpng-version', and
  download compatible DLLs if needed.

  For GIF images, we recommend to use versions 5.0.0 or later of
  giflib, as it is much enhanced wrt previous versions.  You can find
  precompiled binaries and headers for giflib on the ezwinports site,
  http://sourceforge.net/projects/ezwinports/files/.

  Version 5.0.0 and later of giflib are binary incompatible with
  previous versions (the signatures of several functions have
  changed), so Emacs will only look for giflib libraries that are
  compatible with the version it was compiled against.  Similar to
  libpng, that version is given by the value of the Lisp variable
  `libgif-version'; e.g., 50005 means version 5.0.5.  The variable
  `dynamic-library-alist' is automatically set to name only those DLL
  libraries that are known to be compatible with the version given by
  `libgif-version'.

  For JPEG images, you will need libjpeg 6b or later, which will be
  called libjpeg-N.dll, jpeg62.dll, libjpeg.dll, or jpeg.dll.  You can
  find these on the ezwinports site.

  TIFF images require libTIFF 3.0 or later, which will be called
  libtiffN.dll or libtiff-N.dll or libtiff.dll.  These can be found on
  the ezwinports site.

  Pre-built versions of librsvg and its dependencies can be found in
  one of these places:

  1. http://sourceforge.net/projects/ezwinports/files/

     This site includes a minimal (as much as possible for librsvg)
     build of the library and its dependencies; it is also more
     up-to-date with the latest upstream versions.  However, it
     currently only offers 32-bit builds.  For building Emacs, you
     need to download from this site all of the following *-bin.zip
     archives:

       librsvg, gdk-pixbuf, cairo, glib

     The 'bin' archives on this site include both header files and the
     libraries needed for building with librsvg and for running Emacs.
     The librsvg archive includes all the shared libraries needed to
     run Emacs with SVG support; the other 3 packages are required
     because the compiler needs to see their header files when
     building Emacs.

  2. GTK project download site for Windows (see above for 2 URLs,
     either for 32-bit builds or 64-bit builds)

     This is the official Windows download site of the GTK project.
     Its builds of librsvg are fatter, but are currently the only
     alternative for 64-bit builds.  The easiest way to obtain the
     dependencies required for building from this site is to download
     a pre-bundled GTK+ development environment for Windows.  If you
     would nevertheless like to download only the packages that are
     strictly required, then, as of the time of this writing, here's
     the list of GTK+ packages you will need:

        librsvg, pango, freetype-2.4.11, freetype-2.4.2, croco, cairo,
        glib, gdk-pixbuf, fontconfig, libpng-1.4.x, libpng-1.5.x,
        libffi, libxml2, zlib

     The GTK download page provides 2 separate archives for each
     package: a 'bin' (binary) archive with programs and DLLs, and a
     'dev' (development) archive with header files, import libraries,
     and pkg-config files; download and install both archives for each
     package you need.  (Sources of each package are available in a
     separate, 3rd archive.)

     As you see, some libraries for using this site's librsvg are
     needed in more than one version -- this is because librsvg and
     some of its dependencies were linked against different versions
     of those libraries, and will look only for those DLLs when you
     invoke SVG function.  So there's a bit of "DLL hell" involved
     here, but at least in theory this should work, as each library
     will dynamically link only against its dependencies, even if
     another version of the same library is already loaded.  In
     particular, at least 2 different versions of libpng will have to
     be installed on your machine.  When you install these libpng
     versions, be sure to keep the header files and the pkg-config
     files in sync, i.e. install both the 'bin' and 'dev' archives of
     the same libpng version together.

  To use librsvg at runtime, ensure that librsvg and its dependencies
  are on your PATH, or in the same directory as the emacs.exe binary.
  If you are downloading from the ezwinports site, you only need to
  install a single archive, librsvg-X.Y.Z-w32-bin.zip, which includes
  all the dependency DLLs.  For the GTK project site, download the
  'bin' archives for each of the libraries mentioned above.

  If you think you've got all the dependencies and SVG support is
  still not working, check your PATH for other libraries that shadow
  the ones you downloaded.  Libraries of the same name from different
  sources may not be compatible, this problem was encountered in the
  past, e.g., with libcroco from gnome.org.

  If you can see etc/images/splash.svg, then you have managed to get
  SVG support working.  Congratulations for making it through DLL hell
  to this point.  For some SVG images, you'll probably see error
  messages from Glib about failed assertions, or warnings from Pango
  about failure to load fonts (installing the missing fonts should fix
  the latter kind of problems).  Problems have been observed in some
  images that contain text, they seem to be a problem in the Windows
  port of Pango, or maybe a problem with the way Cairo or librsvg is
  using it that doesn't show up on other platforms.  However, Emacs
  should not crash due to these issues.  If you eventually find the
  SVG support too unstable to your taste, you can rebuild Emacs
  without it by specifying the --without-rsvg switch to the configure
  script.

  Binaries for the other image libraries can be found on the
  ezwinports site or at the GnuWin32 project (the latter are generally
  very old, so not recommended).  Note specifically that, due to some
  packaging snafus in the GnuWin32-supplied image libraries, you will
  need to download _source_ packages for some of the libraries in
  order to get the header files necessary for building Emacs with
  image support.

* Optional GnuTLS support

  To compile with GnuTLS, you will need pkg-config to be installed, as
  the configure script invokes pkg-config to find out which compiler
  switches to use for GnuTLS.  See above for the URL where you can
  find pkg-config for Windows.

  You will also need to install the p11-kit package, which is a
  dependency of GnuTLS, and its header files are needed for
  compilation of programs that use GnuTLS.  You can find p11-kit on
  the same site as GnuTLS, see the URL below.

  If the configure script finds the GnuTLS header files and libraries
  on your system, Emacs is built with GnuTLS support by default; to
  avoid that you can pass the argument --without-gnutls.

  In order to support GnuTLS at runtime, a GnuTLS-enabled Emacs must
  be able to find the relevant DLLs during startup; failure to do so
  is not an error, but GnuTLS won't be available to the running
  session.

  You can get pre-built binaries (including any required DLL and the
  header files) at http://sourceforge.net/projects/ezwinports/files/.

* Optional libxml2 support

  To compile with libxml2, you will need pkg-config to be installed,
  as the configure script invokes pkg-config to find out which
  compiler switches to use for libxml2.  See above for the URL where
  you can find pkg-config for Windows.

  If the configure script finds the libxml2 header files and libraries
  on your system, Emacs is built with libxml2 support by default; to
  avoid that you can pass the argument --without-libxml2.

  In order to support libxml2 at runtime, a libxml2-enabled Emacs must
  be able to find the relevant DLLs during startup; failure to do so
  is not an error, but libxml2 features won't be available to the
  running session.

  One place where you can get pre-built Windows binaries of libxml2
  (including any required DLL and the header files) is here:

     http://sourceforge.net/projects/ezwinports/files/

  For runtime support of libxml2, you will also need to install the
  libiconv "development" tarball, because the libiconv headers need to
  be available to the compiler when you compile with libxml2 support.
  A MinGW port of libiconv can be found on the MinGW site:

   http://sourceforge.net/projects/mingw/files/MinGW/Base/libiconv/

  You need the libiconv-X.Y.Z-N-mingw32-dev.tar.lzma tarball from that
  site.

\f
This file is part of GNU Emacs.

GNU Emacs 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 3 of the License, or
(at your option) any later version.

GNU Emacs 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 GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.