|author||Rob Tsuk <email@example.com>||Mon Apr 23 12:31:46 2018 -0700|
|committer||Rob Tsuk <firstname.lastname@example.org>||Mon Apr 23 12:31:46 2018 -0700|
Update README for cross compilation Fixes TO-395. Change-Id: I943e6aa51c76e4e1e25baaa834969ac3c6ba1251
fargo v0.2.0 Fargo is a prototype Fuchsia-specific wrapper around Cargo USAGE: fargo [FLAGS] [OPTIONS] [SUBCOMMAND] FLAGS: --debug-os Use debug user.bootfs and ssh keys -h, --help Prints help information -V, --version Prints version information -v, --verbose Print verbose output while performing commands OPTIONS: -N, --device-name <device-name> Name of device to target, needed if there are multiple devices visible on the network -T, --target-cpu <target-cpu> Architecture of target device [default: x64] [values: x64, arm64] SUBCOMMANDS: autotest Auto build and test in Fuchsia device or emulator build Build binary targeting Fuchsia device or emulator build-tests Build tests for Fuchsia device or emulator cargo Run a cargo command for Fuchsia. Use -- to indicate that all following arguments should be passed to cargo. check Check binary targeting Fuchsia device or emulator configure Run a configure script for the cross compilation environment enable-networking Enable networking for a running emulator help Prints this message or the help of the given subcommand(s) list-devices List visible Fuchsia devices load-driver Build driver and load it on Fuchsia device or emulator. pkg-config Run pkg-config for the cross compilation environment restart Stop all Fuchsia emulators and start a new one run Run binary on Fuchsia device or emulator ssh Open a shell on Fuchsia device or emulator start Start a Fuchsia emulator stop Stop all Fuchsia emulators test Run unit tests on Fuchsia device or emulator
fargo-test directory contains something one can use to test-drive.
Since at the moment fargo requires the FUCHSIA_DIR environmental variable be set to the path to a Fuchsia source tree containing a release build, the first step is to build Fuchsia.
The Fuchsia Getting Started instruction are what you need. Since a release build is what fargo expects to find you‘ll want to pass --args “is_debug=false” to fx/set. You’ll also need to specify
out/debug-x64 as the out directory when using
fx set. The Rust components that fargo needs to cross compile are part of garnet, so you must be using the garnet layer or higher.
The author most often uses the following steps to update and build Fuchsia in preparation for using fargo
./scripts/fx set-layer garnet .jiri_root/bin/jiri update ./scripts/fx set x64 out/release-x64 --args "is_debug=false" ./scripts/fx build-zircon ./scripts/fx build
Once this build is complete, clone and build fargo.
git clone https://fuchsia.googlesource.com/fargo cd fargo cargo install --force
Fargo uses ssh to communicate between your host computer and either Qemu or a real device to copy build results and execute them. For Qemu there is a bit of tricky set up to do.
Finally, you need to be using nightly (as opposed to stable) and have the
x86_64-unknown-fuchsia target installed. If you installed rust with rustup you can install the target with:
rustup default nightly rustup target add x86_64-unknown-fuchsia
If you installed Rust some other way, you'll have to do some research about how to get the nightly build and
x86_64-unknown-fuchsia support into your installation.
Now to verify if fargo is working correctly, try starting a fuchsia machine and executing a test.
fargo start cd fargo/fargo-test fargo test
Note that fargo start now depends on an environment using fx set. If that isn‘t the way you start Fuchsia emulators, use fargo enable-networking after you’ve started the emulator.
If all is well, you should see a successful test pass just as if you had ran cargo test on any other rust project.
Additionally, if you are using qemu you need to enable networking, otherwise fargo won't be able to copy the binary onto then fuchsia machine to run the tests.
Sometimes you want to pass parameters through fargo and cargo and on to something like rustc. To make this easier fargo will convert a “++” parameter to “--” when invoking cargo. For example, the following command:
fargo cargo rustc -- ++ --emit=llvm-ir
will get cargo to cause rustc to emil llvm ir files.
For problems getting the Fuchsia build to complete, the #fuchsia IRC channel on freenode is the best bet.
For fargo itself, that IRC channel can also work of one of the more Rust-aware folks happens to be paying attention. More reliable is the rust-fuchsia Google group.
By default fargo will use the copies of cargo and rustc provided in
$FUCHSIA_DIR/buildtools. To change this behavior, set the environmental variables
FARGO_RUSTC before running fargo.
Some crates are wrappers around libraries written in other languages. An example of one such crate is cairo-rs. Cargo has to know what libraries need to be linked to a binary using such a crate and where to find those libraries.
Cargo uses build.rs files to locate such libraries. This provides a challenge for Fargo, as it is unlikely that such build.rs files would know how to cross compile their libraries for Fuchsia.
Luckily, many of the crates of interest which have native dependencies use pkg-config as one of the ways to find native dependencies. Fargo provides functions to set up and use a Fuchsia-specific pkg-config directory.
fargo pkg-config is a wrapper around pkg-config that sets the environment so that only packages found in the Fuchsia-specific pkg-config directory are visible. This is useful to test if a particular package is already installed.
fargo configure is a wrapper around a package's automake configure script. It takes care of setting up environmental variables such that many automake based packages will properly cross-compile.
scripts/build_cairo_support.sh for an example of how to use these functions to build native support.
fargo sets the following environmental variables before invoking configure:
CC, CXX, RANLIB, LD, AR, CFLAGS, CXXFLAGS, CPPFLAGS LDFLAGS, PKG_CONFIG_PATH, PKG_CONFIG_LIBDIR, PKG_CONFIG_ALL_STATIC
The goal is to transition fargo to using something like an SDK instead.