如何将 `aarch64-none-elf` 添加到我的 Rust 工具链？答案

【问题标题】：How can I add `aarch64-none-elf` to my Rust toolchain?如何将 `aarch64-none-elf` 添加到我的 Rust 工具链？
【发布时间】：2018-08-20 00:46:00
【问题描述】：

今天开始我的 CS140e 工作时，我已经完成了项目的第 3 阶段（编写 C 代码以直接与 Raspberry Pi 3 上的 GPIO 引脚对话，这只会使 LED 闪烁）但是在第 4 阶段，一旦我尝试在 Rust 中编译我的解决方案，rustc 似乎无法找到 aarch64-none-elf 目标：

➜  phase4 git:(master) ✗ make
+ Building target/aarch64-none-elf/release/libblinky.a [xargo --release]
WARNING: the sysroot can't be built for the Stable channel. Switch to nightly.
warning: `panic` setting is ignored for `test` profile
   Compiling rlibc v1.0.0
error[E0463]: can't find crate for `core`
  |
  = note: the `aarch64-none-elf` target may not be installed

error: aborting due to previous error

For more information about this error, try `rustc --explain E0463`.
error: Could not compile `rlibc`.

To learn more, run the command again with --verbose.
Makefile:35: recipe for target 'target/aarch64-none-elf/release/libblinky.a' failed
make: *** [target/aarch64-none-elf/release/libblinky.a] Error 101

事实上，rustc --print target-list 不包括aarch64-none-elf：

➜  phase4 git:(master) ✗ rustc --print target-list
aarch64-linux-android
aarch64-unknown-cloudabi
aarch64-unknown-freebsd
aarch64-unknown-fuchsia
aarch64-unknown-linux-gnu
aarch64-unknown-linux-musl
aarch64-unknown-openbsd
        ...

虽然我已经安装了工具链：

➜  phase4 git:(master) ✗ whereis aarch64-none-elf-gcc
aarch64-none-elf-gcc: /usr/local/bin/aarch64-none-elf/bin/aarch64-none-elf-gcc

另外，我有一个名为aarch64-none-elf.json 的自定义目标文件，其中包含这些内容（大概在构建时传递给xargo）：

{
  "abi-blacklist": [
    "stdcall",
    "fastcall",
    "vectorcall",
    "thiscall",
    "win64",
    "sysv64"
  ],
  "arch": "aarch64",
  "data-layout": "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128",
  "executables": true,
  "linker": "aarch64-none-elf-ld",
  "linker-flavor": "ld",
  "linker-is-gnu": true,
  "llvm-target": "aarch64-unknown-none",
  "no-compiler-rt": true,
  "features": "+a53,+strict-align",
  "max-atomic-width": 128,
  "os": "none",
  "panic": "abort",
  "panic-strategy": "abort",
  "position-independent-executables": true,
  "target-c-int-width": "32",
  "target-endian": "little",
  "target-pointer-width": "64",
  "disable-redzone": true
}

【问题讨论】：

结论是使用 rustup 吗？ ;)
@Stargateur 但看起来 rustup 也没有 aarch64-none-elf 工具链。

标签： rust operating-system arm64 toolchain

【解决方案1】：

结果我需要做的只是运行rustup default nightly 并使用rustc 的夜间版本，如警告中所述，我能够克服该错误。如果有人想解释为什么会这样，那就太好了。

➜  phase4 git:(master) ✗ rustc --version
rustc 1.30.0-nightly (33b923fd4 2018-08-18)

【讨论】：