# Windows

This file describes how to install, or build, and use Julia on Windows.

For more general information about Julia, please see the main README or the documentation.

## General Information for Windows

We highly recommend running Julia using a modern terminal application, in particular Windows Terminal, which can be installed from the Microsoft Store.

### Line endings

Julia uses binary-mode files exclusively. Unlike many other Windows programs, if you write `\n` to a file, you get a `\n` in the file, not some other bit pattern. This matches the behavior exhibited by other operating systems. If you have installed Git for Windows, it is suggested, but not required, that you configure your system Git to use the same convention:

    git config --global core.eol lf
    git config --global core.autocrlf input

or edit `%USERPROFILE%\.gitconfig` and add/edit the lines:

    [core]
        eol = lf
        autocrlf = input

## Binary distribution

For the binary distribution installation notes on Windows please see the instructions at https://julialang.org/downloads/platform/#windows.

## Source distribution

### Cygwin-to-MinGW cross-compiling

The recommended way of compiling Julia from source on Windows is by cross compiling from Cygwin, using versions of the MinGW-w64 compilers available through Cygwin's package manager.

1. Download and run Cygwin setup for 32 bit or 64 bit. Note, that you can compile either 32 or 64 bit Julia from either 32 or 64 bit Cygwin. 64 bit Cygwin has a slightly smaller but often more up-to-date selection of packages.

   Advanced: you may skip steps 2-4 by running:

       setup-x86_64.exe -s <url> -q -P cmake,gcc-g++,git,make,patch,curl,m4,python3,p7zip,mingw64-i686-gcc-g++,mingw64-i686-gcc-fortran,mingw64-x86_64-gcc-g++,mingw64-x86_64-gcc-fortran
       :: replace <url> with a site from https://cygwin.com/mirrors.html
       :: or run setup manually first and select a mirror

2. Select installation location and download mirror.

3. At the 'Select Packages' step, select the following:

   1. From the Devel category: `cmake`, `gcc-g++`, `git`, `make`, `patch`
   2. From the Net category: `curl`
   3. From Interpreters (or Python) category: `m4`, `python3`
   4. From the Archive category: `p7zip`
   5. For 32 bit Julia, and also from the Devel category: `mingw64-i686-gcc-g++` and `mingw64-i686-gcc-fortran`
   6. For 64 bit Julia, and also from the Devel category: `mingw64-x86_64-gcc-g++` and `mingw64-x86_64-gcc-fortran`

4. At the 'Resolving Dependencies' step, be sure to leave 'Select required packages (RECOMMENDED)' enabled.

5. Allow Cygwin installation to finish, then start from the installed shortcut a 'Cygwin Terminal', or 'Cygwin64 Terminal', respectively.

6. Build Julia and its dependencies from source:

   1. Get the Julia sources

          git clone https://github.com/JuliaLang/julia.git
          cd julia

      Tip: If you get an `error: cannot fork() for fetch-pack: Resource temporarily unavailable` from git, add `alias git="env PATH=/usr/bin git"` to `~/.bashrc` and restart Cygwin.

   2. Set the `XC_HOST` variable in `Make.user` to indicate MinGW-w64 cross compilation

          echo 'XC_HOST = i686-w64-mingw32' > Make.user     # for 32 bit Julia
          # or
          echo 'XC_HOST = x86_64-w64-mingw32' > Make.user   # for 64 bit Julia

   3. Start the build

          make -j 4   # Adjust the number of threads (4) to match your build environment.

    > Protip: build both!
    > ```sh
    > make O=julia-win32 configure
    > make O=julia-win64 configure
    > echo 'XC_HOST = i686-w64-mingw32' > julia-win32/Make.user
    > echo 'XC_HOST = x86_64-w64-mingw32' > julia-win64/Make.user
    > echo 'ifeq ($(BUILDROOT),$(JULIAHOME))
    >         $(error "in-tree build disabled")
    >       endif' >> Make.user
    > make -C julia-win32  # build for Windows x86 in julia-win32 folder
    > make -C julia-win64  # build for Windows x86-64 in julia-win64 folder
    > ```

1. Run Julia using the Julia executables directly

       usr/bin/julia.exe
       usr/bin/julia-debug.exe

### Compiling with MinGW/MSYS2

Compiling Julia from source using MSYS2 has worked in the past but is not actively supported. Pull requests to restore support would be welcome. See a past version of this file for the former instructions for compiling using MSYS2.

### Cross-compiling from Unix (Linux/Mac/WSL)

You can also use MinGW-w64 cross compilers to build a Windows version of Julia from Linux, Mac, or the Windows Subsystem for Linux (WSL).

First, you will need to ensure your system has the required dependencies. We need wine (>=1.7.5), a system compiler, and some downloaders. Note: a cygwin install might interfere with this method if using WSL.

On Ubuntu (on other Linux systems the dependency names are likely to be similar):

    apt-get install wine-stable gcc wget p7zip-full winbind mingw-w64 gfortran-mingw-w64
    dpkg --add-architecture i386 && apt-get update && apt-get install wine32 # add sudo to each if needed
    # switch all of the following to their "-posix" variants (interactively):
    for pkg in i686-w64-mingw32-g++ i686-w64-mingw32-gcc i686-w64-mingw32-gfortran x86_64-w64-mingw32-g++ x86_64-w64-mingw32-gcc x86_64-w64-mingw32-gfortran; do sudo update-alternatives --config $pkg; done

On Mac: Install XCode, XCode command line tools, X11 (now XQuartz), and MacPorts or Homebrew. Then run `port install wine wget mingw-w64`, or `brew install wine wget mingw-w64`, as appropriate.

Then run the build:

1. `git clone https://github.com/JuliaLang/julia.git julia-win32`
2. `cd julia-win32`
3. `echo override XC_HOST = i686-w64-mingw32 >> Make.user`
4. `make`
5. `make win-extras` (Necessary before running `make binary-dist`)
6. `make binary-dist` then `make exe` to create the Windows installer.
7. move the `julia-*.exe` installer to the target machine

If you are building for 64-bit windows, the steps are essentially the same. Just replace `i686` in `XC_HOST` with `x86_64`. (note: on Mac, wine only runs in 32-bit mode).

## Debugging a cross-compiled build under wine

The most effective way to debug a cross-compiled version of Julia on the cross-compilation host is to install a windows version of gdb and run it under wine as usual. The pre-built packages available as part of the MSYS2 project are known to work. Apart from the GDB package you may also need the python and termcap packages. Finally, GDB's prompt may not work when launch from the command line. This can be worked around by prepending `wineconsole` to the regular GDB invocation.

## After compiling

Compiling using one of the options above creates a basic Julia build, but not some extra components that are included if you run the full Julia binary installer. If you need these components, the easiest way to get them is to build the installer yourself using `make win-extras` followed by `make binary-dist` and `make exe`. Then running the resulting installer.

## Windows Build Debugging

### GDB hangs with cygwin mintty

- Run gdb under the windows console (cmd) instead. gdb may not function properly under mintty with non- cygwin applications. You can use `cmd /c start` to start the windows console from mintty if necessary.

### GDB not attaching to the right process

- Use the PID from the windows task manager or `WINPID` from the `ps` command instead of the PID from unix style command line tools (e.g. `pgrep`). You may need to add the PID column if it is not shown by default in the windows task manager.

### GDB not showing the right backtrace

- When attaching to the julia process, GDB may not be attaching to the right thread. Use `info threads` command to show all the threads and `thread <threadno>` to switch threads.
- Be sure to use a 32 bit version of GDB to debug a 32 bit build of Julia, or a 64 bit version of GDB to debug a 64 bit build of Julia.

### Build process is slow/eats memory/hangs my computer

- Disable the Windows Superfetch and Program Compatibility Assistant services, as they are known to have spurious interactions with MinGW/Cygwin.

  As mentioned in the link above: excessive memory use by `svchost` specifically may be investigated in the Task Manager by clicking on the high-memory `svchost.exe` process and selecting `Go to Services`. Disable child services one-by-one until a culprit is found.

- Beware of BLODA. The vmmap tool is indispensable for identifying such software conflicts. Use vmmap to inspect the list of loaded DLLs for bash, mintty, or another persistent process used to drive the build. Essentially any DLL outside of the Windows System directory is potential BLODA.

Theme

This document was generated with Documenter.jl version 0.27.12 on Tuesday 22 March 2022. Using Julia version 1.8.0-beta2.