Ensure your CMake version is >= 3.16 with `cmake --version`. If your system doesn't provide a suitable version of CMake, you can download a binary release from the [CMake website](https://cmake.org/download).
Ensure your gcc version is >= 10 with `gcc --version`. Otherwise, install it.
On Ubuntu it's in the repositories of 20.04 (Focal) and later - add the `ubuntu-toolchain-r/test` PPA if you're running an older version:
- osxfuse, e2fsprogs, m4, autoconf, automake, libtool and `BuildFuseExt2.sh` are needed if you want to build the root filesystem disk image natively on macOS. This allows mounting an EXT2 fs and also installs commands like `mke2fs` that are not available on stock macOS.
- Installing osxfuse for the first time requires enabling its system extension in System Preferences and then restarting your machine. The output from installing osxfuse with brew says this, but it's easy to miss.
- If you install some commercial EXT2 macOS fs handler instead of osxfuse and fuse-ext2, you will need to `brew install e2fsprogs` to obtain `mke2fs` anyway.
- As of 2020-08-06, you might need to tell the build system about your newer host compiler. Once you've built the toolchain, navigate to `Build/i686/`, `rm -rf *`, then run `cmake ../.. -G Ninja -DCMAKE_C_COMPILER=gcc-10 -DCMAKE_CXX_COMPILER=g++-10`, then continue with `ninja install` as usual.
- If you are on macOS Big Sur, you will need to manually enable QEMU's acceleration before running Serenity, by creating a new file called `entitlements.xml` in the `Build/` folder, with the content below, and then run the command: `codesign -s - --entitlements entitlements.xml --force /usr/local/bin/qemu-system-x86_64`; otherwise the run command will fail.
<details>
<summary>Content for 'entitlements.xml'.</summary>
```xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN"
For Windows, you will require Windows Subsystem for Linux 2 (WSL2). [Follow the WSL2 instructions here.](https://github.com/SerenityOS/serenity/blob/master/Documentation/NotesOnWSL.md)
Do note the ```Hardware acceleration``` and ```Note on filesystems``` sections, otherwise performance will be terrible.
Once you have installed a distro for WSL2, follow the Linux prerequisites above for the distro you installed, then continue as normal.
Building the toolchain will also automatically create a `Build/i686/` directory for the build to live in. Once the toolchain has been built, go into the `Build/i686/` directory. Specifically, change the current directory to the `Build/` parent directory. To go there from `Toolchain/`, use this command:
Run the following commands from within the `Build/i686/` directory. Note that while `ninja` seems to be faster, you can also just use GNU make, by omitting `-G Ninja` and calling `make` instead of `ninja`:
This will compile all of SerenityOS and install the built files into `Root/` inside the build tree. `ninja` will automatically build as many jobs in parallel as it detects processors; `make` builds only one job in parallel. (Use the `-j` option with an argument if you want to change this.)
On Linux, QEMU is significantly faster if it's able to use KVM. The run script will automatically enable KVM if `/dev/kvm` exists and is readable+writable by the current user.
Bare curious users may even consider sourcing suitable hardware to [install Serenity on a physical PC.](https://github.com/SerenityOS/serenity/blob/master/Documentation/INSTALL.md)
Outside of QEMU, Serenity will run on VirtualBox and VMware. If you're curious, see how to [install Serenity on VirtualBox](https://github.com/SerenityOS/serenity/blob/master/Documentation/VirtualBox.md) or [install Serenity on VMware](https://github.com/SerenityOS/serenity/blob/master/Documentation/VMware.md).
Later on, when you `git pull` to get the latest changes, there's (usually) no need to rebuild the toolchain. You can simply run `ninja install`, `ninja image`, and `ninja run` again. CMake will only rebuild those parts that have been updated.
To add a package from the ports collection to Serenity, for example curl, go into `Ports/curl/` and run `./package.sh`. The sourcecode for the package will be downloaded and the package will be built. After that, rebuild the disk image. The next time you start Serenity, `curl` will be available.
To add, modify or remove files of the disk image's file system, e.g. to change the default keyboard layout, you can create a file with the exact name `sync-local.sh` in the project root (the same directory as `.clang-format`), with content like this:
