docs/devel: add information on how to setup build environments

MacOS and Linux are straightforward, but Windows needs a bit more
details.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Message-Id: <20241209183104.365796-5-pierrick.bouvier@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20250116160306.1709518-35-alex.bennee@linaro.org>

docs/devel/build-environment.rst

@@ -0,0 +1,118 @@
+
+.. _setup-build-env:
+
+Setup build environment
+=======================
+
+QEMU uses a lot of dependencies on the host system. glib2 is used everywhere in
+the code base, and most of the other dependencies are optional.
+
+We present here simple instructions to enable native builds on most popular
+systems.
+
+You can find additional instructions on `QEMU wiki <https://wiki.qemu.org/>`_:
+
+- `Linux <https://wiki.qemu.org/Hosts/Linux>`_
+- `MacOS <https://wiki.qemu.org/Hosts/Mac>`_
+- `Windows <https://wiki.qemu.org/Hosts/W32>`_
+- `BSD <https://wiki.qemu.org/Hosts/BSD>`_
+
+Note: Installing dependencies using your package manager build dependencies may
+miss out on deps that have been newly introduced in qemu.git. In more, it misses
+deps the distribution has decided to exclude.
+
+Linux
+-----
+
+Fedora
+++++++
+
+::
+
+    sudo dnf update && sudo dnf builddep qemu
+
+Debian/Ubuntu
++++++++++++++
+
+You first need to enable `Sources List <https://wiki.debian.org/SourcesList>`_.
+Then, use apt to install dependencies:
+
+::
+
+    sudo apt update && sudo apt build-dep qemu
+
+MacOS
+-----
+
+You first need to install `Homebrew <https://brew.sh/>`_. Then, use it to
+install dependencies:
+
+::
+
+    brew update && brew install $(brew deps --include-build qemu)
+
+Windows
+-------
+
+You first need to install `MSYS2 <https://www.msys2.org/>`_.
+MSYS2 offers `different environments <https://www.msys2.org/docs/environments/>`_.
+x86_64 environments are based on GCC, while aarch64 is based on Clang.
+
+We recommend to use MINGW64 for windows-x86_64 and CLANGARM64 for windows-aarch64
+(only available on windows-aarch64 hosts).
+
+Then, you can open a windows shell, and enter msys2 env using:
+
+::
+
+    c:/msys64/msys2_shell.cmd -defterm -here -no-start -mingw64
+    # Replace -ucrt64 by -clangarm64 or -ucrt64 for other environments.
+
+MSYS2 package manager does not offer a built-in way to install build
+dependencies. You can start with this list of packages using pacman:
+
+Note: Dependencies need to be installed again if you use a different MSYS2
+environment.
+
+::
+
+    # update MSYS2 itself, you need to reopen your shell at the end.
+    pacman -Syu
+    pacman -S \
+        base-devel binutils bison diffutils flex git grep make sed \
+        ${MINGW_PACKAGE_PREFIX}-toolchain \
+        ${MINGW_PACKAGE_PREFIX}-glib2 \
+        ${MINGW_PACKAGE_PREFIX}-gtk3 \
+        ${MINGW_PACKAGE_PREFIX}-libnfs \
+        ${MINGW_PACKAGE_PREFIX}-libssh \
+        ${MINGW_PACKAGE_PREFIX}-ninja \
+        ${MINGW_PACKAGE_PREFIX}-pixman \
+        ${MINGW_PACKAGE_PREFIX}-pkgconf \
+        ${MINGW_PACKAGE_PREFIX}-python \
+        ${MINGW_PACKAGE_PREFIX}-SDL2 \
+        ${MINGW_PACKAGE_PREFIX}-zstd
+
+If you want to install all dependencies, it's possible to use recipe used to
+build QEMU in MSYS2 itself.
+
+::
+
+    pacman -S wget
+    wget https://raw.githubusercontent.com/msys2/MINGW-packages/refs/heads/master/mingw-w64-qemu/PKGBUILD
+    # Some packages may be missing for your environment, installation will still
+    # be done though.
+    makepkg -s PKGBUILD || true
+
+Build on windows-aarch64
+++++++++++++++++++++++++
+
+When trying to cross compile meson for x86_64 using UCRT64 or MINGW64 env,
+configure will run into an error because the cpu detected is not correct.
+
+Meson detects x86_64 processes emulated, so you need to manually set the cpu,
+and force a cross compilation (with empty prefix).
+
+::
+
+    ./configure --cpu=x86_64 --cross-prefix=
+

docs/devel/index-build.rst

@@ -8,6 +8,7 @@ some of the basics if you are adding new files and targets to the build.
    :maxdepth: 3
 
    build-system
+   build-environment
    kconfig
    docs
    qapi-code-gen