# About
`//build` contains:
* Core GN templates and configuration
* Core Python build scripts
Since this directory is DEPS'ed in by some other repositories (webrtc, pdfium,
v8, etc), it should be kept as self-contained as possible by not referring
to files outside of it. Some exceptions exist (`//testing`, select
`//third_party` subdirectories), but new dependencies tend to break these other
projects, and so should be avoided.
Changes to `//build` should be landed in the Chromium repo. They will then be
replicated to the stand-alone [build repo](
https://chromium.googlesource.com/chromium/src/build)
by the [gsubtreed tool.](
https://chromium.googlesource.com/infra/infra/+/main/infra/services/gsubtreed)
Note: You can find all directories already available through gsubtreed in the
[list of all chromium repos](
https://chromium.googlesource.com/).
## Contents
* `//build/config` - Common templates via `.gni` files.
* `//build/toolchain` - GN toolchain definitions.
* `Other .py files` - Some are used by GN/Ninja. Some by gclient hooks, some
are just random utilities.
Files referenced by `//.gn`:
* `//build/BUILDCONFIG.gn` - Included by all `BUILD.gn` files.
* `//build/secondary` - An overlay for `BUILD.gn` files. Enables adding
`BUILD.gn` to directories that live in sub-repositories.
* `//build_overrides` -
Refer to [//build_overrides/README.md](../build_overrides/README.md).
## Docs
* [Writing GN Templates](docs/writing_gn_templates.md)
* [Debugging Slow Builds](docs/debugging_slow_builds.md)
* [Mac Hermetic Toolchains](docs/mac_hermetic_toolchain.md)
* [Android Build Documentation](android/docs/README.md)
