sysroot

• Introduction
• Directory Structure
• Constraints
• Compilation and Building
• Usage
• Repositories Involved

Introduction

sysroot is a root directory used by the Clang compiler to search for standard libraries and header files. The libc library is generated from the open-source musl library by compilation.

Directory Structure

/prebuilts/lite/sysroot
├── build                   # Toolchain building (including build scripts)
├── thirdparty              # Temporary third-party header files required for toolchain building
├── usr                     # C library and header files exposed externally
│   ├── include             # Header files exposed externally
│   │  └── arm-liteos       # Chip architecture for the toolchain
│   └── lib                 # C library exposed externally
│       └── arm-liteos      # Chip architecture for the toolchain

Constraints

sysroot applies only to the OpenHarmony kernel.

Compilation and Building

When bugs in the musl library are fixed or the version is updated, you need to compile and build a new libc library by executing thirdparty_headers.sh and build_musl_clang.sh scripts in the build directory, respectively. The new libc library will be stored in the /prebuilts/lite/sysroot/build/usr directory. Then, you need to replace the header files and libc library in the /prebuilts/lite/sysroot/usr directory.

Usage

• Add the bin directory to the PATH environment variable. For details about how to set up the compilation environment, see Setting Up the Hi3518 Development Environment and Setting Up the Hi3516 Development Environment.
• The following is a sample script for compiling the helloworld.c program:

clang -o helloworld helloworld.c -target arm-liteos -L ~/llvm/lib/clang/9.0.0/lib/arm-liteos/a7_softfp_neon-vfpv4 --sysroot=/usr/xxx/OS/prebuilts/lite/sysroot/

The compiler directory is ~/llvm.

Repositories Involved

Kernel subsystem

prebuilts_lite_sysroot