Migrating a platform to Cobalt 27

Using RDK as our reference platform, we migrated from Cobalt 25 to Cobalt 27 first. You can find most of the required changes in this commit: d7236a995f023bba1c74ad95602f460c2fa72297.

Overview

Below are the high-level steps required to migrate a platform:

  • Add your platform to _COBALT_STARBOARD_PLATFORMS in cobalt/build/gn.py and add an args.gn file for your platform at cobalt/build/configs/<platform_name>/args.gn.

    • Ensure you set the following variables:
    import("//cobalt/build/configs/linux-x64x11-modular/args.gn")
target_os =
target_cpu =
use_evergreen = true
starboard_path =

    Use the appropriate OS and CPU for your target platform, and set the Starboard path to the directory containing your port (for example, the starboard_path for the linux-x64x11 reference platform is starboard/linux/x64x11).

  • Update Starboard functions (this mostly involves removing deprecated functions; see starboard/CHANGELOG.md, but you may need to modify wrappers under //starboard/shared/modular/ if NPLB tests fail).

  • Follow crashpad_integration.md to migrate your platform's Crashpad integration.

  • Some Chromium settings may cause issues. If you run into these issues, contact the Cobalt team so we can address them upstream.

  • Validate with the NPLB test suite and by running Cobalt. Run NPLB via an Evergreen loader instead of directly as an executable.

  • Validate by running YTS, aiming for parity with Cobalt 25 results.

Building and Running

To build Cobalt and NPLB in Evergreen mode:

cobalt/build/gn.py -p <your_platform> -c <config> --no-rbe
autoninja -C out/<your_platform>_<config> cobalt_loader nplb_loader

To run Cobalt:

out/<your_platform>_<config>/cobalt_loader.py

Or, if you need to deploy to a device, i.e., to run NPLB:

tar czpf nplb.tgz -C out/<your_platform>_<config>/ -T out/<your_platform>_<config>/nplb_loader.runtime_deps

# Copy to your device

tar xzpf nplb.tgz
./nplb_loader.py

The helper Python script runs elf_loader_sandbox --evergreen_content=. --evergreen_library=libnplb.so. You can run this manually if you prefer, changing the flag values as necessary.