Build profiles

Needs first: Configure an image

Choose a build profile when an image must be smaller, faster or easier to debug, and profile the build when it takes too long.

nano-ros builds C, C++ and Rust code on your behalf. You choose the optimization level once, on the image, and the build passes it to every crate and library it builds: the cargo profile on the cargo driver, CMAKE_BUILD_TYPE on the CMake one.

Before you start

• A workspace with an image, or a CMake project that adds nano-ros as in Build inside an existing CMake or vendor tree.

Steps

Set the profile on the image

1. Name it in the bringup’s system.toml, on one image or on [image_defaults] for all of them:

   [image_defaults]
   profile = "nros-relwithdebinfo"   # the base every image folds over
   
   [image.linux]
   board = "linux"
   
   [image.mps2]
   board   = "mps2-an385-baremetal"
   profile = "nros-minsizerel"       # this one goes on a board
   

2. Build. You do not repeat the profile on the command line, and you do not define the nros-* profiles anywhere: the build writes them into the image’s generated cargo settings under build/.

   nros build mps2
   

The nros-* profiles and the CMake build types they come from:

Set it from CMake

When you drive CMake yourself, set CMAKE_BUILD_TYPE as in any CMake project, and nano-ros derives the cargo profile for the Rust it builds underneath:

cmake --preset linux -DCMAKE_BUILD_TYPE=MinSizeRel
cmake --build build/linux

The configure prints the profile it chose and the target/ directory it builds into:

-- nano-ros: cargo profile `nros-minsizerel` (CMAKE_BUILD_TYPE=MinSizeRel) → target/nros-minsizerel

Set NROS_CARGO_PROFILE when the two halves should differ, for example a small C++ image with debuggable Rust:

cmake --preset linux \
    -DCMAKE_BUILD_TYPE=MinSizeRel -DNROS_CARGO_PROFILE=nros-relwithdebinfo

An unrecognized build type is an error, never a guess.

Use a profile of your own

Name any profile. When the name is not one of the nros-* profiles, you own its definition, and nano-ros passes the name through and injects nothing:

[profile.prod]
inherits = "release"
opt-level = 3
lto = "fat"

Put it where cargo already looks: the package’s Cargo.toml for a one-package project, or a .cargo/config.toml in a directory above the project. A nano-ros workspace has no root Cargo.toml, and the generated entry under build/ is rewritten on every build. An undefined name fails as cargo always does: error: profile 'prod' is not defined.

Find where the build time goes

nros-build-profile reads the timing files the build already wrote and reports where the time went: code generation, compile and link, which unit dominated, and which crate was built more than once. It never builds anything. The release installs it beside nros; release 0.6.0-nros4 and older do not carry it.

1. For per-crate detail on the cargo driver, build with cargo’s timings. ninja, which the CMake and west drivers use, always writes its log, so those need nothing.

   cargo build --timings --manifest-path build/posix-zenoh/linux_entry/Cargo.toml \
       --config build/posix-zenoh/linux_entry/nros-cargo.toml
   

2. Point it at the directory that holds build*/ or target*/:

   nros-build-profile build/posix-zenoh/linux_entry --deep
   

   It prints a stage table, the slowest units with --deep, and hints. Without cargo’s timings you still get the stage table, and a note on how to get the drill-down.

3. For CI, write it as JSON and compare runs:

   nros-build-profile build/posix-zenoh/linux_entry --json
   

   The hints flag a large C unit built with no compiler cache, a crate compiled more than once, and a job count too high for the RAM. Silence them with --no-hints.

Example

One workspace, a debuggable host image and a small board image:

# src/demo_bringup/system.toml (images)
[image_defaults]
profile = "nros-relwithdebinfo"

[image.linux]
board = "linux"

[image.mps2]
board   = "mps2-an385-baremetal"
profile = "nros-minsizerel"

nros build --all

If it doesn’t work

• A board image is larger than expected. It built at the default, nros-relwithdebinfo, which trades size for build speed. Use nros-minsizerel for a constrained board.
• The profile you chose is not the one used. Two platforms pin their own and say so: NuttX Rust images, and FreeRTOS images under QEMU, which miss zenoh-pico’s handshake window at low optimization.
• error: profile '<name>' is not defined. A profile of your own needs a definition where cargo looks for one; see above.

See also

• Configure an image: the size knobs beside the profile.
• Build outputs: where the target/ directory of each profile lands, and the measured sizes per profile.