Building and Installing Emacs on Windows (from 95 to 7 and beyond) Copyright (C) 2001-2014 Free Software Foundation, Inc. See the end of the file for license conditions. *** This method of building Emacs is no longer supported. *** It may fail to produce a correctly working Emacs. Do not report bugs associated with this build method. Instead, follow the new instructions in INSTALL. * For the impatient Here are the concise instructions for configuring and building the native Windows binary of Emacs, for those who want to skip the complex explanations and ``just do it'': Do not use this recipe with Cygwin. For building on Cygwin, use the normal installation instructions, ../INSTALL. Do not use these instructions with MSYS environment. For building the native Windows binary with MinGW and MSYS, follow the instructions in the file INSTALL in this directory. For building without MSYS, if you have a Cygwin or MSYS port of Bash on your Path, you will be better off removing it from PATH. (For details, search for "MSYS sh.exe" below.) 1. Change to the `nt' directory (the directory of this file): cd nt 2. Run configure.bat. 2a.If you use MSVC, set up the build environment by running the SetEnv.cmd batch file from the appropriate SDK directory. (Skip this step if you are using MinGW.) For example: "C:\Program Files\Microsoft SDKs\Windows\v7.1\Bin\SetEnv.cmd" /x86 /Debug if you are going to compile a debug version, or "C:\Program Files\Microsoft SDKs\Windows\v7.1\Bin\SetEnv.cmd" /x86 /Release if you are going to compile an optimized version. 2b.From the COMMAND.COM/CMD.EXE command prompt type: configure From a Unixy shell prompt: cmd /c configure.bat or command.com /c configure.bat 3. Run the Make utility suitable for your environment. If you build with the Microsoft's Visual C compiler: nmake For the development environments based on GNU GCC (MinGW, MSYS, Cygwin - but see notes about Cygwin make below), depending on how Make is called, it could be: make or mingw32-make or gnumake or gmake (If you are building from Bazaar, say "make bootstrap" or "nmake bootstrap" instead, and avoid using Cygwin make.) With GNU Make, you can use the -j command-line option to have Make execute several commands at once, like this: gmake -j 2 (With versions of GNU Make before 3.82, you need also set the XMFLAGS variable, like this: gmake -j 2 XMFLAGS="-j 2" The XMFLAGS variable overrides the default behavior of version 3.82 and older of GNU Make on Windows, whereby recursive Make invocations reset the maximum number of simultaneous commands to 1. The above command allows up to 4 simultaneous commands at once in the top-level Make, and up to 3 in each one of the recursive Make's.) 4. Generate the Info manuals (only if you are building out of Bazaar, and if you have makeinfo.exe installed): make info (change "make" to "nmake" if you use MSVC). 5. Install the produced binaries: make install That's it! If these short instructions somehow fail, read the rest of this file. * Preliminaries If you want to build a Cygwin port of Emacs, use the instructions in the INSTALL file in the main Emacs directory (the parent of this directory). These instructions are for building a native Windows binary of Emacs. If you used WinZip to unpack the distribution, we suggest to remove the files and unpack again with a different program! WinZip is known to create some subtle and hard to debug problems, such as converting files to DOS CR-LF format, not creating empty directories, etc. We suggest to use djtarnt.exe from the GNU FTP site. For modern formats, such as .tar.xz, we suggest bsdtar.exe from the libarchive package; its precompiled Windows binaries are available from this site: http://sourceforge.net/projects/ezwinports/files/ In addition to this file, if you build a development snapshot, you should also read INSTALL.BZR in the parent directory. * Supported development environments To compile Emacs, you will need either Microsoft Visual C++ 2.0, or later and nmake, or a Windows port of GCC 2.95 or later with MinGW and Windows 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 (latest versions of the Cygwin toolkit, at least since v1.3.3, include the MinGW headers and libraries as an integral part). The rest of this file assumes you have a working development environment. If you just installed such an environment, try building a trivial C "Hello world" program, and see if it works. If it doesn't work, resolve that problem first! If you use Microsoft Visual Studio .NET 2003, don't forget to run the VCVARS32.BAT batch file from the `Bin' subdirectory of the directory where you have installed VS.NET. With other versions of MSVC, run the SetEnv.cmd batch file from the `Bin' subdirectory of the directory where you have the SDK installed. If you use the MinGW port of GCC and GNU Make to build Emacs, there are some compatibility issues wrt Make and the shell that is run by Make, either the standard COMMAND.COM/CMD.EXE supplied with Windows or sh.exe, a port of a Unixy shell. For reference, below 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. Note that any version of Make that is compiled with Cygwin will only work with Cygwin tools, due to the use of Cygwin style paths. This means Cygwin Make is unsuitable for building parts of Emacs that need to invoke Emacs itself (leim and "make bootstrap", for example). Also see the Trouble-shooting section below if you decide to go ahead and use Cygwin make. In addition, using 4NT or TCC as your shell is known to fail the build process, at least since 4NT version 3.01. Use CMD.EXE, the default Windows shell, instead. MSYS sh.exe also appears to cause various problems, e.g., it is known to cause failures in commands like "cmd /c FOO" in the Makefiles, because it thinks "/c" is a Unix-style file name that needs conversion to the Windows format. If you have MSYS installed, try "make SHELL=cmd.exe" to force the use of cmd.exe instead of the MSYS sh.exe. sh exists no sh cygwin b20.1 make (3.75): fails[1, 5] fails[2, 5] 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[4] cygwin compiled gmake 3.77: fails[1, 5] fails[2, 5] cygwin compiled make 3.78.1: fails[5] fails[2, 5] cygwin compiled make 3.79.1: fails[3, 5] fails[2?, 5] cygwin compiled make 3.80: okay[6] fails?[7] cygwin compiled make 3.81: fails fails?[7] mingw32 compiled make 3.79.1: okay okay mingw32 compiled make 3.80: okay okay[7] mingw32 compiled make 3.81: okay okay[8] Notes: [1] doesn't cope with makefiles with DOS line endings, so must mount emacs source with text!=binary. [2] fails when needs to invoke shell commands; okay invoking gcc etc. [3] requires LC_MESSAGES support to build; cannot build with early versions of Cygwin. [4] may fail on Windows 9X and Windows ME; if so, install Bash. [5] fails when building leim due to the use of cygwin style paths. May work if building emacs without leim. [6] need to uncomment 3 lines in nt/gmake.defs that invoke `cygpath' (look for "cygpath" near line 85 of gmake.defs). [7] not recommended; please report if you try this combination. [8] tested only on Windows XP. Other compilers may work, but specific reports from people that have tried suggest that the Intel C compiler (for example) may produce an Emacs executable with strange filename completion behavior. Unless you would like to assist by finding and fixing the cause of any bugs like this, we recommend the use of the supported compilers mentioned in the previous paragraph. You will also need a copy of the POSIX cp, rm and mv programs. These and other useful POSIX utilities can be obtained from one of several projects: * http://gnuwin32.sourceforge.net/ ( GnuWin32 ) * http://www.mingw.org/ ( MinGW ) * http://www.cygwin.com/ ( Cygwin ) * http://unxutils.sourceforge.net/ ( UnxUtils ) If you build Emacs on 16-bit versions of Windows (9X or ME), we suggest to install the Cygwin port of Bash. That is because the native Windows shell COMMAND.COM is too limited; the Emacs build procedure tries very hard to support even such limited shells, but as none of the Windows developers of Emacs work on Windows 9X, we cannot guarantee that it works without a more powerful shell. Additional instructions and help for building Emacs on Windows can be found at the Emacs Wiki: http://www.emacswiki.org/cgi-bin/wiki/WThirtyTwoInstallationKit and on these URLs: http://ourcomments.org/Emacs/w32-build-emacs.html http://derekslager.com/blog/posts/2007/01/emacs-hack-3-compile-emacs-from-cvs-on-windows.ashx Both of those pages were written before Emacs switched from CVS to Bazaar, but the parts about building Emacs still apply in Bazaar. The second URL has instructions for building with MSVC, as well as with MinGW, while the first URL covers only MinGW, but has more details about it. * Configuring 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.bat' with no options. To see what options are available, run `configure --help'. Do NOT use the --no-debug option to configure.bat unless you are absolutely sure the produced binaries will never need to be run under a debugger. Because of limitations of the stock Windows command shells, special care is needed to pass some characters in the arguments of the --cflags and --ldflags options. Backslashes should not be used in file names passed to the compiler and linker via these options. Use forward slashes instead. If the arguments to these two options include the `=' character, like when passing a -DFOO=bar preprocessor option, the argument with the `=' character should be enclosed in quotes, like this: configure --cflags "-DFOO=bar" Support for options that include the `=' character require "command extensions" to be enabled. (They are enabled by default, but your system administrator could have changed that. See "cmd /?" for details.) If command extensions are disabled, a warning message might be displayed informing you that "using parameters that include the = character by enclosing them in quotes will not be supported." You may also use the --cflags and --ldflags options to pass additional parameters to the compiler and linker, respectively; they are frequently used to pass -I and -L flags to specify supplementary include and library directories. If a directory name includes spaces, you will need to enclose it in quotes, as follows -I"C:/Program Files/GnuTLS-2.10.1/include". Note that only the directory name is enclosed in quotes, not the entire argument. Also note that this functionality is only supported if command extensions are available. If command extensions are disabled and you attempt to use this functionality you may see the following warning message "Error in --cflags argument: ... Backslashes and quotes cannot be used with --cflags. Please use forward slashes for filenames and paths (e.g. when passing directories to -I)." 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 suppressed because of limitations in the Windows 9X command.com shell. You are encouraged to look at the file config.log which shows details for failed tests, after configure.bat finishes. Any unexplained failure should be investigated and perhaps reported as a bug (see the section about reporting bugs in the file README in this directory and in the Emacs manual). * 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 when the configure script is run. This can be setup using environment variables, or by specifying --cflags -I... options on the command-line to configure.bat. The configure script will report whether it was able to detect the headers. 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; using backslashes will cause compiler warnings or errors about unrecognized escape sequences. 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). Binaries for the image libraries (among many others) can be found at the GnuWin32 project. PNG, JPEG and TIFF libraries are also included with GTK, which is installed along with other Free Software that requires it. These are built with MinGW, but they can be used with both GCC/MinGW and MSVC builds of Emacs. See the info on http://ourcomments.org/Emacs/w32-build-emacs.html, under "How to Get Images Support", for more details about installing image support libraries. 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. If GTK 2.0 is installed, addpm will arrange for its image libraries to be on the DLL search path for Emacs. 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). 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. * Optional GnuTLS support If configure.bat finds the gnutls/gnutls.h file in the include path, 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 If configure.bat finds the libxml/HTMLparser.h file in the include path, 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/ To compile Emacs with libxml2 from that site, you will need to pass the "--cflags -I/path/to/include/libxml2" option to configure.bat, because libxml2 header files are installed in the include/libxml2 subdirectory of the directory where you unzip the binary distribution. Other binary distributions might use other directories, although include/libxml2 is the canonical place where libxml2 headers are installed on Posix platforms. 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. * Experimental SVG support SVG support is currently experimental, and not built by default. Specify --with-svg and ensure you have all the dependencies in your include path. Unless you have built a minimalist librsvg yourself (untested), librsvg depends on a significant chunk of GTK+ to build, plus a few Gnome libraries, libxml2, libbz2 and zlib at runtime. The easiest way to obtain the dependencies required for building is to download a pre-bundled GTK+ development environment for Windows. GTK puts its header files all over the place, so you will need to run pkgconfig to list the include path you will need (either passed to configure.bat as --cflags options, or set in the environment). To use librsvg at runtime, ensure that librsvg and its dependencies are on your PATH. If you didn't build librsvg yourself, you will need to check with where you downloaded it from for the dependencies, as there are different build options. If it is a short list, then it most likely only lists the immediate dependencies of librsvg, but the dependencies themselves have dependencies - so don't download individual libraries from GTK+, download and install the whole thing. 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 with libbzip2 from GnuWin32 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. You'll probably find that some SVG images crash Emacs. 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. * Optional extra runtime checks The configure.bat option --enable-checking builds Emacs with some optional extra runtime checks and assertions enabled. This may be useful for debugging. * Optional extra libraries You can pass --lib LIBNAME option to configure.bat to cause Emacs to link with the specified library. You can use this option more than once. * Building After running configure, simply run the appropriate `make' program for your compiler to build Emacs. For MSVC, this is nmake; for GCC, it is GNU make. (If you are building out of Bazaar, say "make bootstrap" or "nmake bootstrap" instead.) 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. With GNU Make, you can use the -j command-line option to have Make execute several commands at once, like this: gmake -j 4 XMFLAGS="-j 3" The XMFLAGS variable overrides the default behavior of GNU Make on Windows, whereby recursive Make invocations reset the maximum number of simultaneous commands to 1. The above command allows up to 4 simultaneous commands at once in the top-level Make, and up to 3 in each one of the recursive Make's; you can use other numbers of jobs, if you wish. If you are building from Bazaar, the following commands will produce the Info manuals (which are not part of the Bazaar sources): make info or nmake info Note that you will need makeinfo.exe (from the GNU Texinfo package) in order for this command to succeed. * Installing To install Emacs after it has compiled, simply run `nmake install' or `make install', depending on which version of the Make utility do you have. 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 (for `nmake', type "nmake install INSTALL_DIR=D:/emacs" instead). The install process will run addpm to setup the registry entries, and to create a Start menu icon for Emacs. * Make targets The following make targets may be used by users building the source distribution, or users who have checked out of Bazaar after an initial bootstrapping. make Builds Emacs from the available sources and pre-compiled lisp files. make install Installs programs to the bin directory, and runs addpm to create Start Menu icons. 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. 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. Note that this will not remove installed files, or the results of builds performed with different compiler or optimization options than the current configuration. After make distclean, it is necessary to run configure.bat followed by make to rebuild. make cleanall Removes object and executable files that may have been created by previous builds with different configure options, in addition to the files produced by the current configuration. make realclean Removes the installed files in the bin subdirectory in addition to the files removed by make cleanall. make dist Builds Emacs from the available sources and pre-compiled lisp files. Packages Emacs binaries as full distribution and barebin distribution. The following targets are intended only for use with the Bazaar sources. make bootstrap Creates a temporary emacs binary with lisp source files and uses it to compile the lisp files. Once the lisp files are built, emacs is redumped with the compiled lisp. make recompile Recompiles any changed lisp files after an update. This saves doing a full bootstrap after every update. If this or a subsequent make fail, you probably need to perform a full bootstrap, though running this target multiple times may eventually sort out the interdependencies. make maintainer-clean Removes everything that can be recreated, including compiled lisp files, to get back to the state of a fresh Bazaar tree. After make maintainer-clean, it is necessary to run configure.bat and make bootstrap to rebuild. Occasionally it may be necessary to run this target after an update. * Creating binary distributions Binary distributions (full and barebin distributions) can be automatically built and packaged from source tarballs or a bzr checkout. When building Emacs binary distributions, the --distfiles argument to configure.bat specifies files to be included in the bin directory of the binary distributions. This is intended for libraries that are not built as part of Emacs, e.g. image libraries. For example, specifying --distfiles D:\distfiles\libXpm.dll results in libXpm.dll being copied from D:\distfiles to the bin directory before packaging starts. Multiple files can be specified using multiple --distfiles arguments: --distfiles D:\distfiles\libXpm.dll --distfiles C:\jpeglib\jpeg.dll For packaging the binary distributions, the 'dist' make target uses 7-Zip (http://www.7-zip.org), which must be installed and available on the Windows Path. * Trouble-shooting The main problems that are likely to be encountered when building Emacs stem from using an old version of GCC, or old MinGW or Windows 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. Older versions of the Windows API headers that come with Cygwin and MinGW may be missing some definitions required by Emacs, or broken in other ways. In particular, uniscribe APIs were added to MinGW CVS only on 2006-03-26, so releases from before then cannot be used. When in doubt about correctness of what configure did, look at the file config.log, which shows all the failed test programs and compiler messages associated with the failures. If that doesn't give a clue, please report the problems, together with the relevant fragments from config.log, as bugs. 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.) If you are using certain Cygwin builds of GCC, such as Cygwin version 1.1.8, you may need to specify some extra compiler flags like so: configure --with-gcc --cflags -mwin32 --cflags -D__MSVCRT__ --ldflags -mwin32 However, the latest Cygwin versions, such as 1.3.3, don't need those switches; you can simply use "configure --with-gcc". We will attempt to auto-detect the need for these flags in a future release. * Debugging 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. (GDB for Windows is available from the MinGW site, http://www.mingw.org/download.shtml.) When Emacs aborts due to a fatal internal error, Emacs on Windows pops up an Emacs Abort Dialog asking you whether you want to debug Emacs or terminate it. If Emacs was built with MSVC, click YES twice, and Windbg or the DevStudio debugger will start up automatically. If Emacs was built with GCC, first start GDB and attach it to the Emacs process with the "gdb -p EMACS-PID" command, where EMACS-PID is the Emacs process ID (which you can see in the Windows Task Manager), type the "continue" command inside GDB, and only then click YES on the abort dialog. This will pass control to the debugger, and you will be able to debug the cause of the fatal error. The single most important thing to find out when Emacs aborts or crashes is where did that happen in the Emacs code. This is called "backtrace". Emacs on Windows uses more than one thread. When Emacs aborts due to a fatal error, the current thread may not be the application thread running Emacs code. Therefore, to produce a meaningful backtrace from a debugger, you need to instruct it to show the backtrace for every thread. With GDB, you do it like this: (gdb) thread apply all backtrace To run Emacs under a debugger to begin with, simply start it from the debugger. With GDB, chdir to the `src' directory (if you have the source tree) or to a directory with the `.gdbinit' file (if you don't have the source tree), and type these commands: C:\whatever\src> gdb x:\path\to\emacs.exe (gdb) run Thereafter, use Emacs as usual; you can minimize the debugger window, if you like. The debugger will take control if and when Emacs crashes. 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 a 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. Therefore, 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, pop up 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() 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 threads. 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 .