Bazel compatibility constraints

pw_build: Integrations for Bazel, GN, and CMake

The pw_build module provides a limited selection of Bazel compatibility constraints under @pigweed//pw_build/constraints/ that are helpful for targeting embedded platforms. These are guided by Pigweed Bazel build compatibility patterns.

The selection of offered constraints are intentionally limited to reduce the difficulty of properly configuring an embedded platform.

ARM

Constraint Setting: @pigweed//pw_build/constraints/arm:mcpu

This constraint_setting corresponds to the -mcpu compiler flag for ARM processors, and is the primary constraint used to guide Upstream Pigweed toolchains for ARM platforms.

Additionally, @pigweed//pw_build/constraints/arm:lists.bzl provides the ALL_CORTEX_M_CPUS list for convenience.

Board

Constraint Setting: @pigweed//pw_build/constraints/board:board

Deprecated. Do not use, and do not extend. If you see usages of these, consider removing them.

Chipset

Constraint Setting: @pigweed//pw_build/constraints/chipset:chipset

Deprecated. Do not use, and do not extend. If you see usages of these, consider removing them.

RISC-V

Extensions

Constraint Settings: @pigweed//pw_build/constraints/riscv/extensions:*

These boolean constraints define the enabled instruction extensions of the targeted RISC-V processor, which are the primary mechanism used to configure Upstream Pigweed toolchains for RSIC-V platforms.

RTOS

Constraint Setting: @pigweed//pw_build/constraints/rtos:rtos

Identifies the target Real-Time Operating System. This is considered orthogonal to the traditional @platforms//os constraint. This allows MCUs to have both @platforms//os:none and @pigweed//pw_build/constraints/rtos:freertos constraints.

Rust

Constraint Setting: @pigweed//pw_build/constraints/rust:std_enabled

Indicates whether the Rust std library is enabled. This is primarily used to control the available selection of crates.io dependencies.