Cross compilation fails (for armv7-unknown-linux-gnueabihf)

[eflukx]

When trying to compile the example on Ubuntu x64 (WSL2) for Raspberry Pi 3 (i.e. armv7-unknown-linux-gnueabihf), compilation fails. This (AFAICS) has to do with the failing cross compilation of some native libraries: pkg_config failed: pkg-config has not been configured to support cross-compilation.

Just wanted to add this issue for future reference for other users bumping into this same issue. Found this issue on the dbus-rs repo outlining the problem and offering a (rather complicated) solution. Haven't tried it yet, but seems promising.

Expected Behavior

Successful compilation of the example.

Actual Behavior

❯ cargo build --target armv7-unknown-linux-gnueabihf --example testing
   Compiling libdbus-sys v0.2.2
   Compiling quote v1.0.15
   Compiling num-traits v0.2.14
error: failed to run custom build command for `libdbus-sys v0.2.2`

Caused by:
  process didn't exit successfully: `/home/eflukx/code-native/networkmanager-rs/target/debug/build/libdbus-sys-3da2e4d0d9fbb5c1/build-script-build` (exit status: 101)
  --- stdout
  cargo:rerun-if-env-changed=DBUS_1_NO_PKG_CONFIG
  cargo:rerun-if-env-changed=PKG_CONFIG_ALLOW_CROSS_armv7-unknown-linux-gnueabihf
  cargo:rerun-if-env-changed=PKG_CONFIG_ALLOW_CROSS_armv7_unknown_linux_gnueabihf
  cargo:rerun-if-env-changed=TARGET_PKG_CONFIG_ALLOW_CROSS
  cargo:rerun-if-env-changed=PKG_CONFIG_ALLOW_CROSS
  cargo:rerun-if-env-changed=PKG_CONFIG_armv7-unknown-linux-gnueabihf
  cargo:rerun-if-env-changed=PKG_CONFIG_armv7_unknown_linux_gnueabihf
  cargo:rerun-if-env-changed=TARGET_PKG_CONFIG
  cargo:rerun-if-env-changed=PKG_CONFIG
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR_armv7-unknown-linux-gnueabihf
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR_armv7_unknown_linux_gnueabihf
  cargo:rerun-if-env-changed=TARGET_PKG_CONFIG_SYSROOT_DIR
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR

  --- stderr
  pkg_config failed: pkg-config has not been configured to support cross-compilation.

  Install a sysroot for the target platform and configure it via
  PKG_CONFIG_SYSROOT_DIR and PKG_CONFIG_PATH, or install a
  cross-compiling wrapper for pkg-config and set it via
  PKG_CONFIG environment variable.
  One possible solution is to check whether packages
  'libdbus-1-dev' and 'pkg-config' are installed:
  On Ubuntu:
  sudo apt install libdbus-1-dev pkg-config
  On Fedora:
  sudo dnf install dbus-devel pkgconf-pkg-config

  thread 'main' panicked at 'explicit panic', /home/eflukx/.cargo/registry/src/garden.eu.org-1ecc6299db9ec823/libdbus-sys-0.2.2/build.rs:16:9
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
warning: build failed, waiting for other jobs to finish...
error: build failed

Steps to Reproduce the Problem

1. sudo apt install libdbus-1-dev pkg-config
2. cargo build --target armv7-unknown-linux-gnueabihf --example testing
3. see it fail

[IniterWorker]

Hi @eflukx,

You should check your env/sdk/rootfs.

One possible solution is to check whether packages
  'libdbus-1-dev' and 'pkg-config' are installed:

networkmanager-rs is building fine under Tier 2:

. /opt/poky/3.4.1/.../environment-setup-cortexa7t2hf-neon-poky-linux-gnueabi
[7:08:17] initerworker:networkmanager-rs git:(master) $ cargo build --target armv7-unknown-linux-gnueabihf --release
Finished release [optimized] target(s) in 8.22s

B.r,