Frequently Asked Questions#

Is Pigweed a framework?#

There are three core components of Pigweed’s offering:

  1. The environment setup system (bootstrap and activate)

  2. The GN-based build and test system

  3. The individual modules (mostly C++ code)

We consider #1 and #2 combined as the “Pigweed Monolith” - since it has an integrated environment setup and build system. However, this part of the system is entirely optional; it is not only possible, but encouraged to take individual modules (like for example pw_tokenizer or pw_ring_buffer) and integrate them into your existing environment setup approach and build system.

So, to answer the question:

  1. Is Pigweed’s environment setup system a framework? No. This component solves (a) downloading compilers and (b) setting up a Python virtual environment; what you do with the environment is up to you.

  2. Is Pigweed’s GN-based build & test setup system a framework? In short, yes. This is the most framework-like part of Pigweed, since you build your code using Pigweed’s GN-based primitives. However, it is optional.

  3. Are Pigweed’s C++ modules a framework? No. They are libraries you can independently take into your project and use like any other C++ library.

Isn’t C++ bloated and slow?#

In general, no, but it is important to follow some guidelines as discussed in the Embedded C++ Guide.

At Google, we have made some quantitative analysis of various common embedded patterns in C++ to evaluate the cost of various constructs. We will open source this work at some point.

How do I setup Pigweed for my project?#

Attention

This FAQ entry should be an entire article, but isn’t one yet; sorry!

To use Pigweed, you must decide the answer to one question: Do you wish to use the Pigweed integrated environment and build, or just use individual modules?

A la carte: Individual modules only#

This option can work for small projects with a pre-existing build system in place. Large projects will probably need a more maintainable and scalable solution.

To use the libraries, submodule or copy the relevant Pigweed modules into your project, and use them like any other C++ library. You’ll need to also copy over the transitive dependencies of any module you use. You can find a module’s transitive dependencies by inspecting its build files. If your project uses CMake, you can directly import Pigweed’s build from your project with CMake’s external project system, or just use a CMake include statement.

Monolith: Using the integrated system#

This may be a good option if you are starting a new project. However, there is a gap in our documentation and examples at the moment; sorry about that! You may need to ask us for help; try the mailing list or chat room.

Note: Pigweed isn’t quite ready for masses of projects to use the whole system just yet. We will be offering examples and material for this eventually.

The summary is:

  • Create a new repository

  • Add Pigweed as a submodule; we suggest under third_party/pigweed or vendor/pigweed. It is also possible to use Android’s repo tool, but we suggest submodules.

  • Create your own BUILD.gn and BUILDCONFIG.gn; we suggest starting by copying the ones from Pigweed. You’ll need to create your own toplevel targets like those in Pigweed’s root BUILD.gn.

  • Create a bootstrap script in your project root that optionally does some project specific setup, then invokes the Pigweed upstream bootstrap (or in the other order).

  • If you have custom hardware, you will want to create a target. See the targets/ directory for examples like the STM32F429i-Discovery.

Attention

This section is incomplete; if you need help please reach out in chat or on the mailing list. We know this part of Pigweed is incomplete and will help those who are interested in giving Pigweed a try.

Why doesn’t Pigweed allow shell scripting?#

Pigweed supports multiple platforms. The native shells on these differ and additionally “compatible” shells often have sububle differences in behavior. Pigweed uses Python instead of shell scripting wherever practical and changes to Pigweed that include shell scripting will likely be rejected. Users of Pigweed may use shell scripts in their own code and we have included support for Shellcheck during presubmit checks that is automatically enabled if shellcheck found in the path.

What development hosts are supported?#

We support the following platforms:

Development host

Comments

Linux on x86-64

Most recent Linux distributions will work.

macOS on arm64

Support in progress, file bugs for any issues. Control whether Rosetta is used via pigweed.json.

macOS on x86-64

Mojave or newer should work.

Windows 10 on x86-64

Native Windows only; WSL1 or 2 not supported.

Docker on x86-64

Containers based on Ubuntu 18.04 and newer.

Attention

In all of the above supported platforms, the support is contingent on using Pigweed’s bootstrap (env setup) system. While it is possible to use Pigweed without bootstrap, it is unsupported and undocumented at this time.

Partially supported host platform: Chrome OS#

Chromebooks are able to run some of the Pigweed components; notably all the “host” target builds and runs. However, due to USB access issues, it is not possible to flash and run on real hardware (like for example the STM32F429i Discovery).

To run on ChromeOS:

  1. Enable the Linux shell

  2. sudo apt-install build-essential

  3. Go through Pigweed setup.

What about other host platforms?#

There are two key issues that make running the host tooling on other platforms challenging:

  1. Availability of up-to-date compilers

  2. Availability of up-to-date Python

For both of these, Pigweed relies on Google-maintained binaries packaged in CIPD, which includes daily builds of LLVM, and recent versions of the ARM GCC toolchains. Platforms other than Mac/Windows/Linux running on x86-64 will need to provide equivalent binaries, which is some effort.

Host platforms that we are likely to support in the future#

  • Linux on ARM - We do not support ARM-based Linux host platforms. However, we would like to support this eventually. In many cases we have configured things so packages are downloaded correctly when on this platform

  • Windows on WSL2 x86-64 - There are some minor issues preventing WSL2 on Windows from being a smooth experience, but we are working on them.

Platforms that we are unlikely to support#

  • Anything on x86-32 - While it’s possible 32-bit x86 could be made to work, we don’t have enough users to make this worthwhile. If this is something you are interested in and would be willing to support, let us know.

Why name the project Pigweed?#

Pigweed, also known as amaranth, is a nutritious grain and leafy salad green that is also a rapidly growing weed. When developing the project that eventually became Pigweed, we wanted to find a name that was fun, playful, and reflective of how we saw Pigweed growing. Teams would start out using one module that catches their eye, and after that goes well, they’d quickly start using more.

So far, so good 😁

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