slint-rust-template build fails on ARMv7 - missing libraries

[OOHehir]

Bug Description

The rust template breaks on armv7 builds due missing libraries, details below. I've tried to installing libudev-dev:armhf but looks like there are issues getting these. Is the best way to point the build at a sysroot or is there a work around?

Many thanks!

error: failed to run custom build command for `libudev-sys v0.1.4`

Caused by:
  process didn't exit successfully: `/home/repo/hello_world_slint_rust/target/release/build/libudev-sys-c3b4aed72c1bb4e6/build-script-build` (exit status: 101)
  --- stdout
  cargo:rerun-if-env-changed=LIBUDEV_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

  thread 'main' (1046574) panicked at /home/owen/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/libudev-sys-0.1.4/build.rs:38:41:
  called `Result::unwrap()` on an `Err` value: "pkg-config has not been configured to support cross-compilation.\n\nInstall a sysroot for the target platform and configure it via\nPKG_CONFIG_SYSROOT_DIR and PKG_CONFIG_PATH, or install a\ncross-compiling wrapper for pkg-config and set it via\nPKG_CONFIG environment variable."
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Reproducible Code (if applicable)

slint-rust-template project

# Cargo.toml
[package]
name = "hello_world_slint_rust"
version = "0.1.0"
edition = "2021"

[dependencies]
slint = "1.14.1"
gpio-cdev = "0.6"

[target.'cfg(target_os = "linux")'.dependencies]
slint = {version = "1.14.1", default-features = false, features = ["backend-linuxkms-noseat", "renderer-software"] }

[build-dependencies]
slint-build = "1.14.1"

# config.toml
[profile.release]
opt-level = "z"          # small binaries for embedded
lto = true
strip = true
codegen-units = 1

[profile.dev]
opt-level = 1

[target.armv7-unknown-linux-gnueabi]
linker = "arm-linux-gnueabi-gcc"
rustflags = ["-C", "target-feature=+crt-static"]

[target.armv7-unknown-linux-gnueabihf]
linker = "arm-linux-gnueabihf-gcc"
rustflags = ["-C", "target-feature=+crt-static"]

Environment Details

• Slint Version: 1.14.1
• Platform/OS: Linux Mint 21.1 Cinnamon
• Programming Language: Rust
• Backend/Renderer: backend-linuxkms-noseat, renderer-software"

Product Impact

No response

[ogoffart]

Are you cross-compiling?
If yes, how are you cross compiling? Are you using Cross?
( This is what we recommend in

slint/docs/building.md

Line 184 in bbd5d85

## Cross-Compiling

)

[OOHehir]

@ogoffart Thanks, that seems to work!

It looks like the runtime dependencies are DRM/KMS, libdrm/libgbm, libinput + udev, glibc with backend-linuxkms-noseat & renderer-software if I'm correct?

[ogoffart]

That looks correct. This should be documented there. https://docs.slint.dev/latest/docs/slint/guide/backends-and-renderers/backend_linuxkms/#dependencies
Please let is know if that is not accurate.

[OOHehir]

Thanks @ogoffart, I think I'm getting somewhere but my Rust setup isn't correct. How does one pass custom features (for the backend) when using cross? This is my 'hello-word' example which contains:

[target.armv7-unknown-linux-gnueabihf.dependencies]    # hard float
slint = { version = "1.14.1", default-features = false, features = ["backend-linuxkms-noseat", "renderer-software"] }

But the runtime is still looking for libgbm.

[tronical]

I think the problem is this line in your Cargo.toml:

[dependencies]
slint = "1.14.1"

Despite disabling default features in the other lines, here they remain enabled. That way the femtovg renderer is enabled, which requires gbm.

I suggest to disable default features here and enable compat-1-2.

[OOHehir]

Many thanks @tronical , working now for both arm & native builds. For anyone else here is a simple setup.

BTW @tronical @ogoffart there doesn't seem to be a cross setup for a armv7 soft float, not sure how important/ difficult it is to achieve.