WAMR Porting Guide

WAMR porting guide

This document describes how to port WAMR to a new platform "new-os"

Step 1: Implement platform API layer

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Firstly create the folder for platform API layer implementations:

• for common platforms, create a folder in core/shared/platform/new-os in WAMR repository folder, so the implementation can be upstreamed

• for platforms that are internal and its implementation shouldn't be published, it's recommended to create a folder outside of the WAMR repository folder (e.g. have separate repository for platform API layer implementation)

In the folder you just created, you must provide the following files:

• platform_internal.h: It can be used for any platform-specific definitions such as macros, data types and internal APIs.

• shared_platform.cmake: the cmake file will be included by the building script. It is recommended to add a definition for your platform:

  • add_definitions(-DBH_PLATFORM_YOUR_NAME)

Then go to implement the APIs defined in the following header files for the platform abstraction layer:

• platform_api_vmcore.h: mandatory for building mini-product (vmcore only). Part of the APIs is needed only for Ahead of Time compilation support.

• platform_api_extension.h: mandatory for app-mgr and app-framework. Given that the app-mgr and app-framework are not required for your target platform, you won't have to implement the API defined in the platform_api_extension.h.

common/posix:

There is posix based implementation of the platform API located in the platform/common/posix folder. You can include it if your platform supports posix API. refer to platform linux implementation.

common/math:

Some platforms such as ZephyrOS don't provide math functions e.g. sqrt, fabs and isnan, then you should include source files under the folder platform/common/math.

Step 2: Create the mini product for the platform

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You can build a mini WAMR product which is only the vmcore for your platform. Normally you need to implement the main function which loads a WASM file and run it with the WASM runtime. You don't have to do this step if there is no mini-product need for your platform porting.

Firstly create folder product-mini/platforms/new-os for the platform mini product build, then refer to the linux platform mini-product for creating the CMakeList.txt and the C implementations.

You should set cmake variable WAMR_BUILD_PLATFORM to your platform name while building the mini product. It can be done in the mini product CMakeList.txt file, or pass arguments to cmake command line like:

mkdir build
cd build
cmake .. -DWAMR_BUILD_PLATFORM=new-os

For platform implementations that are outside of the WAMR repository (e.g. internal platforms), you also need to provide SHARED_PLATFORM_CONFIG path:

cmake .. -DWAMR_BUILD_PLATFORM=new-os -DSHARED_PLATFORM_CONFIG=/path/to/new-os/shared_platform.cmake

Refer to build_wamr.md for the building configurations and parameters.