Building and Installing Emacs
on Windows NT and Windows 95/98/2000
To compile Emacs, you will need either Microsoft Visual C++ 2.0 or
later, or a Windows port of GCC 2.95 or later with Mingw and W32 API
support and a port of GNU make. You can use the Cygwin ports of GCC,
but Emacs requires the Mingw headers and libraries to build.
If you build Emacs on Windows 9X or ME, not on Windows 2000 or
Windows/NT, we suggest to install the Cygwin port of Bash.
Please see http://www.mingw.org for pointers to GCC/Mingw binaries.
For reference, here is a list of which builds of GNU make are known
to work or not, and whether they work in the presence and/or absence
of sh.exe, the Cygwin port of Bash.
sh exists no sh
cygwin b20.1 make (3.75): okay fails
MSVC compiled gmake 3.77: okay okay
MSVC compiled gmake 3.78.1: okay okay
MSVC compiled gmake 3.79.1: okay okay
mingw32/gcc-2.92.2 make (3.77): okay okay
cygwin compiled gmake 3.77: okay fails
cygwin compiled gmake 3.78.1: okay fails
cygwin compiled gmake 3.79.1: couldn't build make
 doesn't cope with makefiles with DOS line endings, so must mount
emacs source with text!=binary.
 fails when needs to invoke shell commands; okay invoking gcc etc.
 requires LC_MESSAGES support to build; maybe 2.95.x update to
cygwin provides this?
 may fail on Windows 9X and Windows ME; if so, install Bash.
Configuration of Emacs is now handled by running configure.bat in the
nt subdirectory. It will detect which compiler you have available,
and generate makefiles accordingly. You can override the compiler
detection, and control optimization and debug settings, by specifying
options on the command line when invoking configure.
To configure Emacs to build with GCC or MSVC, whichever is available,
simply change to the nt subdirectory and run `configure' with no
options. To see what options are available, run `configure --help'.
N.B. It is normal to see a few error messages output while configure
is running, when gcc support is being tested. These cannot be
surpressed because of limitations in the Windows 9x command.com shell.
After running configure, simply run the appropriate `make' program for
your compiler to build Emacs. For MSVC, this is nmake; for GCC, it is
As the files are compiled, you will see some warning messages
declaring that some functions don't return a value, or that some data
conversions will be lossy, etc. You can safely ignore these messages.
The warnings may be fixed in the main FSF source at some point, but
until then we will just live with them.
To install Emacs after it has compiled, simply run `make install'.
By default, Emacs will be installed in the location where it was
built, but a different location can be specified either using the
--prefix option to configure, or by setting INSTALL_DIR when running
make, like so:
make install INSTALL_DIR=D:/emacs
The install process will run addpm to setup the registry entries, and
to create a Start menu icon for Emacs.
The main problems that are likely to be encountered when building
Emacs stem from using an old version of GCC, or old Mingw or W32 API
headers. Additionally, cygwin ports of GNU make may require the Emacs
source tree to be mounted with text!=binary, because the makefiles
generated by configure.bat necessarily use DOS line endings. Also,
cygwin ports of make must run in UNIX mode, either by specifying
--unix on the command line, or MAKE_MODE=UNIX in the environment.
When configure runs, it attempts to detect when GCC itself, or the
headers it is using, are not suitable for building Emacs. GCC version
2.95 or later is needed, because that is when the Windows port gained
sufficient support for anonymous structs and unions to cope with some
definitions from winnt.h that are used by addsection.c. The W32 API
headers that come with Cygwin b20.1 are incomplete, and do not include
some definitions required by addsection.c, for instance. Also, older
releases of the W32 API headers from Anders Norlander contain a typo
in the definition of IMAGE_FIRST_SECTION in winnt.h, which
addsection.c relies on. Versions of w32api-xxx.zip from at least
1999-11-18 onwards are okay.
If configure succeeds, but make fails, install the Cygwin port of
Bash, even if the table above indicates that Emacs should be able to
build without sh.exe. (Some versions of Windows shells are too dumb
for Makefile's used by Emacs.)
You should be able to debug Emacs using the debugger that is
appropriate for the compiler you used, namely DevStudio or Windbg if
compiled with MSVC, or gdb if compiled with gcc.
Emacs functions implemented in C use a naming convention that reflects
their names in lisp. The names of the C routines are the lisp names
prefixed with 'F', and with dashes converted to underscores. For
example, the function call-process is implemented in C by
Fcall_process. Similarly, lisp variables are prefixed with 'V', again
with dashes converted to underscores. These conventions enable you to
easily set breakpoints or examine familiar lisp variables by name.
Since Emacs data is often in the form of a lisp object, and the
Lisp_Object type is difficult to examine manually in the MSVC
debugger, Emacs provides a helper routine called debug_print that
prints out a readable representation of a Lisp_Object. (If you are
using gdb, there is a .gdbinit file in the src directory which
provides definitions that are useful for examining lisp objects. The
following tips are mainly of interest when using MSVC.) The output
from debug_print is sent to stderr, and to the debugger via the
OutputDebugString routine. The output sent to stderr should be
displayed in the console window that was opened when the emacs.exe
executable was started. The output sent to the debugger should be
displayed in its "Debug" output window.
When you are in the process of debugging Emacs and you would like to
examine the contents of a Lisp_Object variable, popup the QuickWatch
window (QuickWatch has an eyeglass symbol on its button in the
toolbar). In the text field at the top of the window, enter
debug_print(<variable>) and hit return. For example, start and run
Emacs in the debugger until it is waiting for user input. Then click
on the Break button in the debugger to halt execution. Emacs should
halt in ZwUserGetMessage waiting for an input event. Use the Call
Stack window to select the procedure w32_msp_pump up the call stack
(see below for why you have to do this). Open the QuickWatch window
and enter debug_print(Vexec_path). Evaluating this expression will
then print out the contents of the lisp variable exec-path.
If QuickWatch reports that the symbol is unknown, then check the call
stack in the Call Stack window. If the selected frame in the call
stack is not an Emacs procedure, then the debugger won't recognize
Emacs symbols. Instead, select a frame that is inside an Emacs
procedure and try using debug_print again.
If QuickWatch invokes debug_print but nothing happens, then check the
thread that is selected in the debugger. If the selected thread is
not the last thread to run (the "current" thread), then it cannot be
used to execute debug_print. Use the Debug menu to select the current
thread and try using debug_print again. Note that the debugger halts
execution (e.g., due to a breakpoint) in the context of the current
thread, so this should only be a problem if you've explicitly switched