This file covers a few advanced scenarios that go beyond what the basic build guide provides.
## Customizing the disk image
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.
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_KERNEL_COVERAGE_COLLECTION`: enables the KCOV API and kernel coverage collection instrumentation. Only useful for coverage guided kernel fuzzing.
-`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 and the SerenityOS userland.
-`UNDEFINED_BEHAVIOR_IS_FATAL`: makes all undefined behavior sanitizer errors non-recoverable. This option reduces the performance overhead of `ENABLE_UNDEFINED_SANITIZER`.
-`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 -O2 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.
-`ENABLE_KERNEL_LTO`: builds the kernel with link-time optimization.
-`ENABLE_MOLD_LINKER`: builds the userland with the [`mold` linker](https://github.com/rui314/mold). `mold` can be built by running `Toolchain/BuildMold.sh`.
-`ENABLE_JAKT`: builds the `jakt` compiler as a Lagom host tool and enables building applications and libraries that are written in the jakt language.
-`JAKT_SOURCE_DIR`: `jakt` developer's local checkout of the jakt programming language for rapid testing. To use a local checkout, set to an absolute path when changing the CMake cache of Lagom. e.g. ``cmake -S Meta/Lagom -B Build/lagom -DENABLE_JAKT=ON -DJAKT_SOURCE_DIR=/home/me/jakt``
-`INCLUDE_WASM_SPEC_TESTS`: downloads and includes the WebAssembly spec testsuite tests. In order to use this option, you will need to install `prettier` and `wabt`. wabt version 1.0.23 or higher is required to pre-process the WebAssembly spec testsuite.
-`SERENITY_TOOLCHAIN`: Specifies whether to use the established GNU toolchain, or the experimental Clang-based toolchain for building SerenityOS. See the [Clang-based toolchain](#clang-based-toolchain) section below.
-`BUILD_<component>`: builds the specified component, e.g. `BUILD_HEARTS` (note: must be all caps). Check the components.ini file in your build directory for a list of available components. Make sure to run `ninja clean` and `rm -rf Build/x86_64/Root` after disabling components. These options can be easily configured by using the `ConfigureComponents` utility. See the [Component Configuration](#component-configuration) section below.
-`ENABLE_NETWORK_DOWNLOADS`: allows downloading files from the internet during the build. Default on, turning off enables offline builds. For offline builds, the structure of the SERENITY_CACHE_DIR must be set up the way that the build expects.
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 or change a build option, see the [CMake Cache Manipulation](#cmake-cache-manipulation) section below.
## CMake Cache Manipulation
CMake caches variables and options in the binary directory. This allows a developer to tailor variables that are `set()` within the persistent configuration cache.
There are three main ways to manipulate the cache:
-`cmake path/to/binary/dir -DVAR_NAME=Value`
-`ccmake` (TUI interface)
-`cmake-gui`
Options can be set via the initial `cmake` invocation that creates the binary directory to set the initial cache for the binary directory.
Once the binary directory exists, any of the three options above can be used to change the value of cache variables.
For example, boolean options such as `ENABLE_<setting>` or `<component_name>_DEBUG` can be enabled with the value `ON` and disabled with `OFF`:
For more information on how the CMake cache works, see the CMake guide for [Running CMake](https://cmake.org/runningcmake/). Additional context is available in the CMake documentation for
[variables](https://cmake.org/cmake/help/latest/manual/cmake-language.7.html#variables) and [set()](https://cmake.org/cmake/help/latest/command/set.html#set-cache-entry).
## SuperBuild configuration
Serenity uses host tools written in idiomatic Serenity C++ to generate code and data for the main target build.
The "SuperBuild" pattern helps to separate the host build of core Serenity libraries from the target build of the
entire operating system environment. The SuperBuild allows clear separation of the host and target builds in the project's CMakeLists
and unifies the approach taken towards different compiler toolchains and architectures.
The recommended way to build and run the system, `./Meta/serenity.sh run`, invokes the SuperBuild equivalently to the commands below:
The CMake configuration of the `superbuild-<arch>` directory configures two [ExternalProjects](https://cmake.org/cmake/help/latest/module/ExternalProject.html).
The first project is `lagom`, which is the host build of the project. For more information on Lagom, see the [Lagom ReadMe](../Meta/Lagom/ReadMe.md). It is used
to build all the code generators and other host tools needed for the main Serenity build. The second project is the main build, which compiles the system for the
target architecture using the selected toolchain.
The `superbuild-<arch>` configuration also generates the [CMake toolchain file](https://cmake.org/cmake/help/latest/manual/cmake-toolchains.7.html#cross-compiling)
for the selected compiler toolchain and architecture via the `-DSERENITY_ARCH` and `-DSERENITY_TOOLCHAIN` arguments to the SuperBuild configuration step.
The Serenity project depends on the install step of the Lagom build, as it uses [find_package](https://cmake.org/cmake/help/latest/command/find_package.html) to locate
the host tools for use in the code generation custom commands.
The SuperBuild build steps are roughly equivalent to the following commands:
Directing future `ninja` or `cmake --build` invocations to the `superbuild-<arch>` directory ensures that any headers or cpp files shared between the
host and target builds will be rebuilt, and the new host tools and libraries will be staged to the lagom-install directory. This is where the superbuild
differs from manually entering the commands above, it establishes a dependency between the install stage of lagom and the configure/build stages of Serenity.
The main limitation of the SuperBuild is that any non-option CMake cache variables such as component configuration or debug flag settings must be done
after a build has started. That is, the CMakeCache.txt for the Serenity and Lagom builds is not created until the SuperBuild build starts and reaches the
proper stage for the build in question. For more information on the CMake cache see the [CMake Cache Manipulation](#cmake-cache-manipulation) section above.
The debug flags might be manipulated after a build per the following commands:
```console
# Initial build, generate binary directories for both child builds
It requires `whiptail` as a dependency, which is available on most systems in the `newt` or `libnewt` package. To build and run it, run the following commands from the `Build/x86_64` directory:
This will prompt you which build type you want to use and allows you to customize it by manually adding or removing certain components. It will then run a CMake command based on the selection as well as `ninja clean` and `rm -rf Root` to remove old build artifacts.
## Tests
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.
## Running SerenityOS with VirtualBox and VMware
Outside of QEMU, Serenity will run on VirtualBox and VMware. If you're curious, see how to [install Serenity on VirtualBox](VirtualBox.md) or [install Serenity on VMware](VMware.md).
## Running SerenityOS on bare metal
Bare curious users may even consider sourcing suitable hardware to [install Serenity on a physical PC.](BareMetalInstallation.md)
and re-install with ``cd Toolchain/Build/clang/llvm && cmake ../../../Tarballs/llvm-project-$LLVM_VERSION.src/llvm -DCLANG_ENABLE_CLANGD=ON && ninja install/strip``, where $LLVM_VERSION should be tab-completable in your shell.
Some OS distributions don't ship bleeding-edge clang-format binaries. Below are 3 options to acquire an updated clang-format tool, in order of preference:
1) If you have a Debian-based (apt-based) distribution, use the [LLVM apt repositories](https://apt.llvm.org) to install the latest release of clang-format.
2) Compile the SerenityOS-patched LLVM from source using ``Toolchain/BuildClang.sh`` as described above and use the compiled ``Toolchain/Local/clang/bin/clang-format`` binary in your editor and terminal. The meta-lint-ci pre-commit hook will automatically pick up the Toolchain clang-format binary.
3) Compile LLVM from source as described in the LLVM documentation [here](https://llvm.org/docs/GettingStarted.html#compiling-the-llvm-suite-source-code).
