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 [QEMU](https://www.qemu.org/) version is >= 5 with `qemu-system-i386 -version`. Otherwise, install it. You can also build it using the `Toolchain/BuildQemu.sh` script.
On Ubuntu gcc-10 is available in the repositories of 20.04 (Focal) and later - add the `ubuntu-toolchain-r/test` PPA if you're running an older version:
First, make sure you have enabled the `community` repository in `/etc/apk/repositories` and run `apk update`. It has been tested on `edge`, YMMV on `stable`.
- 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.
There are some optional features that can be enabled during compilation that are intended to help with specific types of development work or introduce experimental features. Currently, the following build options are available:
-`ENABLE_ADDRESS_SANITIZER` and `ENABLE_KERNEL_ADDRESS_SANITIZER`: builds in runtime checks for memory corruption bugs (like buffer overflows and memory leaks) in Lagom test cases and the kernel, respectively.
-`ENABLE_MEMORY_SANITIZER`: enables runtime checks for uninitialized memory accesses in Lagom test cases.
-`ENABLE_UNDEFINED_SANITIZER`: builds in runtime checks for [undefined behavior](https://en.wikipedia.org/wiki/Undefined_behavior) (like null pointer dereferences and signed integer overflows) in Lagom test cases.
-`ENABLE_FUZZER_SANITIZER`: builds [fuzzers](https://en.wikipedia.org/wiki/Fuzzing) for various parts of the system.
-`ENABLE_EXTRA_KERNEL_DEBUG_SYMBOLS`: sets -Og and -ggdb3 compile options for building the Kernel. Allows for easier debugging of Kernel code. By default, the Kernel is built with -Os instead.
-`ENABLE_ALL_THE_DEBUG_MACROS`: used for checking whether debug code compiles on CI. This should not be set normally, as it clutters the console output and makes the system run very slowly. Instead, enable only the needed debug macros, as described below.
-`ENABLE_ALL_DEBUG_FACILITIES`: used for checking whether debug code compiles on CI. Enables both `ENABLE_ALL_THE_DEBUG_MACROS` and `ENABLE_EXTRA_KERNEL_DEBUG_SYMBOLS`.
-`ENABLE_COMPILETIME_FORMAT_CHECK`: checks for the validity of `std::format`-style format string during compilation. Enabled by default.
-`ENABLE_PCI_IDS_DOWNLOAD`: downloads the [`pci.ids` database](https://pci-ids.ucw.cz/) that contains information about PCI devices at build time, if not already present. Enabled by default.
-`BUILD_LAGOM`: builds [Lagom](../Meta/Lagom/ReadMe.md), which makes various SerenityOS libraries and programs available on the host system.
-`PRECOMPILE_COMMON_HEADERS`: precompiles some common headers to speedup compilation.
-`ENABLE_KERNEL_LTO`: builds the kernel with link-time optimization.
Many parts of the SerenityOS codebase have debug functionality, mostly consisting of additional messages printed to the debug console. This is done via the `<component_name>_DEBUG` macros, which can be enabled individually at build time. They are listed in [this file](../Meta/CMake/all_the_debug_macros.cmake).
To toggle a build option, add it to the `cmake` command invocation with a `-D` prefix. To enable it, add `=ON` at the end, or add `=OFF` to disable it. The complete command should look similarly to this:
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.
For information on running host and target tests, see [Running Tests](RunningTests.md). The documentation there explains the difference between host tests run with Lagom and
target tests run on SerenityOS. It also contains useful information for debugging CI test failures.
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 shell script with the name `sync-local.sh` in the project root, with content like this:
This will configure your keymap to German (`de`) instead of US English. See [`Base/res/keymaps/`](../Base/res/keymaps/) for a full list. Note that the `keymap` program itself will also modify the `/etc/Keyboard.ini` config file, but this way the change will persist across image rebuilds.
