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Auto merge of #88952 - skrap:add-armv7-uclibc, r=nagisa
Add new tier-3 target: armv7-unknown-linux-uclibceabihf This change adds a new tier-3 target: armv7-unknown-linux-uclibceabihf This target is primarily used in embedded linux devices where system resources are slim and glibc is deemed too heavyweight. Cross compilation C toolchains are available [here](https://toolchains.bootlin.com/) or via [buildroot](https://buildroot.org). The change is based largely on a previous PR #79380 with a few minor modifications. The author of that PR was unable to push the PR forward, and graciously allowed me to take it over. Per the [target tier 3 policy](https://github.com/rust-lang/rfcs/blob/master/text/2803-target-tier-policy.md), I volunteer to be the "target maintainer". This is my first PR to Rust itself, so I apologize if I've missed things!
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compiler/rustc_target/src/spec/armv7_unknown_linux_uclibceabihf.rs
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use crate::spec::{Target, TargetOptions}; | ||
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// This target is for uclibc Linux on ARMv7 without NEON or | ||
// thumb-mode. See the thumbv7neon variant for enabling both. | ||
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pub fn target() -> Target { | ||
let base = super::linux_uclibc_base::opts(); | ||
Target { | ||
llvm_target: "armv7-unknown-linux-gnueabihf".to_string(), | ||
pointer_width: 32, | ||
data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".to_string(), | ||
arch: "arm".to_string(), | ||
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options: TargetOptions { | ||
// Info about features at https://wiki.debian.org/ArmHardFloatPort | ||
features: "+v7,+vfp3,-d32,+thumb2,-neon".to_string(), | ||
cpu: "generic".to_string(), | ||
max_atomic_width: Some(64), | ||
mcount: "_mcount".to_string(), | ||
abi: "eabihf".to_string(), | ||
..base | ||
}, | ||
} | ||
} |
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src/doc/rustc/src/platform-support/armv7-unknown-linux-uclibceabihf.md
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# armv7-unknown-linux-uclibceabihf | ||
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**Tier: 3** | ||
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This tier supports the ARMv7 processor running a Linux kernel and uClibc-ng standard library. It provides full support for rust and the rust standard library. | ||
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## Designated Developers | ||
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* [@skrap](https://github.com/skrap) | ||
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## Requirements | ||
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This target is cross compiled, and requires a cross toolchain. You can find suitable pre-built toolchains at [bootlin](https://toolchains.bootlin.com/) or build one yourself via [buildroot](https://buildroot.org). | ||
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## Building | ||
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### Get a C toolchain | ||
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Compiling rust for this target has been tested on `x86_64` linux hosts. Other host types have not been tested, but may work, if you can find a suitable cross compilation toolchain for them. | ||
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If you don't already have a suitable toolchain, download one [here](https://toolchains.bootlin.com/downloads/releases/toolchains/armv7-eabihf/tarballs/armv7-eabihf--uclibc--bleeding-edge-2020.08-1.tar.bz2), and unpack it into a directory. | ||
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### Configure rust | ||
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The target can be built by enabling it for a `rustc` build, by placing the following in `config.toml`: | ||
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```toml | ||
[build] | ||
target = ["armv7-unknown-linux-uclibceabihf"] | ||
stage = 2 | ||
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[target.armv7-unknown-linux-uclibceabihf] | ||
# ADJUST THIS PATH TO POINT AT YOUR TOOLCHAIN | ||
cc = "/TOOLCHAIN_PATH/bin/arm-buildroot-linux-uclibcgnueabihf-gcc" | ||
``` | ||
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### Build | ||
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```sh | ||
# in rust dir | ||
./x.py build --stage 2 | ||
``` | ||
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## Building and Running Rust Programs | ||
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To test cross-compiled binaries on a `x86_64` system, you can use the `qemu-arm` [userspace emulation](https://qemu-project.gitlab.io/qemu/user/main.html) program. This avoids having a full emulated ARM system by doing dynamic binary translation and dynamic system call translation. It lets you run ARM programs directly on your `x86_64` kernel. It's very convenient! | ||
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To use: | ||
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* Install `qemu-arm` according to your distro. | ||
* Link your built toolchain via: | ||
* `rustup toolchain link stage2 ${RUST}/build/x86_64-unknown-linux-gnu/stage2` | ||
* Create a test program | ||
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```sh | ||
cargo new hello_world | ||
cd hello_world | ||
``` | ||
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* Build and run | ||
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```sh | ||
CARGO_TARGET_ARMV7_UNKNOWN_LINUX_UCLIBCEABIHF_RUNNER="qemu-arm -L ${TOOLCHAIN}/arm-buildroot-linux-uclibcgnueabihf/sysroot/" \ | ||
CARGO_TARGET_ARMV7_UNKNOWN_LINUX_UCLIBCEABIHF_LINKER=${TOOLCHAIN}/bin/arm-buildroot-linux-uclibcgnueabihf-gcc \ | ||
cargo +stage2 run --target armv7-unknown-linux-uclibceabihf | ||
``` |