Compilation and Building Guidelines

• Directory Structure
• Component-based Building Procedure

Directory Structure

build/lite                      # Primary directory for compilation and building
├── components                  # Component description file
├── hb                          # hb pip installation package
├── make_rootfs                 # make script for the file system
├── config                      # Compilation configuration items
│   ├── component               # Definitions of component-related templates, including static libraries, dynamic libraries, extension components, and emulator libraries
│   ├── kernel                  # Compilation configuration parameters of the kernel
│   └── subsystem               # Subsystem template
├── ndk                         # NDK-related compilation scripts and configuration parameters
└── toolchain                   # Compilation toolchains, which contain the compiler directories, compilation options, and linking options

Component-based Building Procedure

1. Add the component compilation script.

   The compilation script language for the component is GN. For details about its basic usage, see the GN Quick Start Guide. In GN, a component is a compilation unit, which can be a static library, a dynamic library, or an executable file.

   The following example adds a script to compile the hello_world component (as an executable file).

   executable("hello_world") {
     include_dirs = [
       "include",
      ]
     sources = [
       "src/hello_world.c"
     ]
   }

   The added script is used to compile hello_world that can run on OpenHarmony.

2. Add the component description.

   The component description is stored in the build/lite/components directory. New components must be added to the JSON file of the corresponding subsystem. A component description must contain the following fields:

   • component: name of the component
   • description: one-sentence description of the component
   • optional: whether the component is optional
   • dirs: source code directory of the component
   • targets: component compilation entry

   For example, to add the hello_world component to the application subsystem, add the hello_world object to the applications.json file.

   {
     "components": [
       {
         "component": hello_world",
         "description": "Hello world.",
         "optional": "true",
         "dirs": [
           "applications/sample/hello_world"
         ],
         "targets": [
           "//applications/sample/hello_world"
         ]
       },
       ...
      ]
   }

3. Configure the component for the product.

   The product configuration file is stored in the vendor/company/ directory. The file must contain the product name, OpenHarmony version, device vendor, development board name, kernel type, kernel version, and the subsystem and component to configure. The following example adds the hello_world component to the my_product.json configuration file:

   {
       "product_name": "hello_world_test",
       "ohos_version": "OpenHarmony 1.0",
       "device_company": "hisilicon",
       "board": "hispark_taurus",
       "kernel_type": "liteos_a",
       "kernel_version": "1.0.0",
       "subsystems": [
         {
           "subsystem": "applications",
           "components": [
             { "component": "hello_world", "features":[] }
           ]
         },
         ...
       ]
   }

4. Compile the component or product.

   1. Run hb set and select hello_world_test@hisilicon.

   2. To build the hello_world component, run the following command:

      hb build hello_world

      To build the hello_world_test product, run the following command:

      hb build