GNU Emacs Installation Guide for the DJGPP (a.k.a. MS-DOS) port

Copyright (C) 1992, 1994, 1996-1997, 2000-2025 Free Software Foundation,
Inc.
See the end of the file for license conditions.

The DJGPP port of GNU Emacs builds and runs on all versions of
MS-Windows from version 3.X on, including Windows XP, Vista, and
Windows 7 (however, see below for issues with Windows Vista and 7).
Building on plain MS-DOS is supported only if long file names are
supported (e.g., with a specialized driver such as doslfn).

To build and install the DJGPP port, you need to have the DJGPP ports
of GCC (the GNU C compiler), GNU Make, rm, mv, cp, and sed, and
version 2.02 or later of DJGPP itself.  See the remarks in CONFIG.BAT
for more information about locations and versions.  The Emacs FAQ (see
info/efaq.info) includes pointers to Internet sites where you can find
the necessary utilities; search for "MS-DOS".  The configuration step
(see below) will test for these utilities and will refuse to continue
if any of them isn't found.

You should carefully choose the version of GCC you use to build Emacs,
because recent versions of GCC don't support building Emacs very well.
The main issue is the debug info: the DJGPP build of Emacs must use
the COFF debug info.  GCC support for COFF debug info was steadily
deteriorating since GCC 5, and GCC 8.1 officially stopped supporting
the -gcoff switch, which the Emacs build process needs.  We recommend
using GCC 3.4.X and Binutils 2.26; GDB 7.2 is capable to debug an
Emacs binary built by this combination.

Bootstrapping Emacs or recompiling Lisp files in the `lisp'
subdirectory using the various targets in the lisp/Makefile file
requires additional utilities: `find' (from Findutils), GNU `echo' and
`test' (from Sh-utils or Coreutils), `ls' and `chmod' (from Fileutils
or Coreutils), `grep' (from Grep), and a port of Bash.  However, you
should not normally need to run lisp/Makefile, as all the Lisp files
are distributed in byte-compiled form as well.  As for bootstrapping
itself, you will only need that if you check-out development sources
from the Emacs source repository.

Building the DJGPP version of Emacs is supported only on systems which
support long file names (e.g. Windows 9X or Windows XP).  You need to
unpack Emacs distribution in a way that doesn't truncate the original
long filenames to the DOS 8.3 namespace; the easiest way to do this is
to use djtar program which comes with DJGPP, since it will behave
consistently with the rest of DJGPP tools.  Do _not_ disable the DJGPP
long-file-name support (a.k.a. "LFN") while building Emacs.

(By the time you read this, you have already unpacked the Emacs
distribution, but if the explanations above imply that you should have
done it differently, it's safer to delete the directory tree created
by the unpacking program and unpack Emacs again, than to risk running
into strange problems during the build process.)

To unpack Emacs with djtar, type this command:

    djtar -x emacs.tgz

(This assumes that the Emacs distribution is called `emacs.tgz' on
your system.)

When unpacking Emacs is done, a directory called `emacs-XX.YY' will be
created, where XX.YY is the Emacs version.

If you want to print international characters, install the intlfonts
distribution.  For this, create a directory called `fonts' under the
`emacs-XX.YY' top-level directory created by unpacking emacs.tgz,
chdir into the directory `emacs-XX.YY/fonts', and type this:

    djtar -x intlfonts.tgz

To build and install Emacs, chdir to the `emacs-XX.YY' directory and
type these commands:

    config msdos
    make install

Running "config msdos" checks for several programs that are required
to configure and build Emacs; if one of those programs is not found,
CONFIG.BAT stops and prints an error message.

On Windows NT and Windows 2000/XP and later, running "config msdos"
might print an error message like "VDM has been already loaded".  This
is because those systems have a program called `redir.exe' which is
incompatible with a program by the same name supplied with DJGPP,
which is used by config.bat.  To resolve this, move the DJGPP's `bin'
subdirectory to the front of your PATH environment variable.

Windows Vista and later has several bugs in its DPMI server related to
memory allocation: it fails DPMI resize memory block function, and it
arbitrarily limits the default amount of DPMI memory to 32MB.  To work
around these bugs, first configure Emacs to use the `malloc' function
from the DJGPP library.  To this end, run CONFIG.BAT with the
"--with-system-malloc" option:

    config --with-system-malloc msdos
    make install

In addition, for Windows Vista you'll need to install Service Pack 1
(SP1) or later and enlarge its DPMI memory limit by setting the value
of this Registry key:

  HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Wow\DpmiLimit

Create this key if it does not exist.  The value is a DWORD; setting
it to 536870912 should let Emacs use up to 512MB of memory.

If you have other problems, either building Emacs or running the
produced binary, look in the file etc/PROBLEMS for some known problems
related to the DJGPP port (search for "MS-DOS").

To install the international fonts, chdir to the intlfonts-X.Y
directory created when you unpacked the intlfonts distribution (X.Y is
the version number of the fonts' distribution), and type the following
command:

    make bdf INSTALLDIR=..

After Make finishes, you may remove the directory intlfonts-X.Y; the
fonts are installed into the fonts/bdf subdirectory of the top-level
Emacs directory, and that is where Emacs will look for them by
default.

Building Emacs creates executable files in the src and lib-src
directories.  Installing the DJGPP port of Emacs moves these
executables to a sibling directory called bin.  For example, if you
build in directory C:/emacs, installing moves the executables from
C:/emacs/src and C:/emacs/lib-src to the directory C:/emacs/bin, so
you can then delete the subdirectories C:/emacs/src and
C:/emacs/lib-src if you wish.  The only subdirectories you need to
keep are bin, lisp, etc and info.  (If you installed intlfonts, keep
the fonts directory and all its subdirectories as well.)  The bin
subdirectory should be added to your PATH.  The msdos subdirectory
includes a PIF and an icon file for Emacs which you might find useful
if you run Emacs under MS Windows.

Emacs on MSDOS finds the lisp, etc and info directories by looking in
../lisp, ../etc and ../info, starting from the directory where the
Emacs executable was run from.  You can override this by setting the
environment variables EMACSDATA (for the location of `etc' directory),
EMACSLOADPATH (for the location of `lisp' directory) and INFOPATH (for
the location of the `info' directory).

Emacs features which require asynchronous subprocesses that depend on
multitasking do not work in the DJGPP port.  Synchronous subprocesses
do work, so features such as compilation, grep, and Ispell run
synchronously, unlike on other platforms.


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 <https://www.gnu.org/licenses/>.
