1. 编译命令修改为

   cargo build --target aarch64-unknown-none-softfloat.json

2. 项目目录下新建.cargo/config.toml文件，内容如下

   [unstable]
   build-std = ["core", "compiler_builtins"] 

原先编译命令

cargo build --target aarch64-unknown-none-softfloat

会报错如下：

error: linking with rust-lld failed: exit status: 1
|
= note: "rust-lld" "-flavor" "gnu" "/home/yuanzhiqiu/os/yzqos_armv8/target/aarch64-unknown-none-softfloat/debug/deps/yzqos_armv8-b39476ede8baa276.358o59hkt7efruo.rcgu.o" "/home/yuanzhiqiu/os/yzqos_armv8/target/aarch64-unknown-none-softfloat/debug/deps/yzqos_armv8-b39476ede8baa276.4t21rnm557dy8f08.rcgu.o" "/home/yuanzhiqiu/os/yzqos_armv8/target/aarch64-unknown-none-softfloat/debug/deps/yzqos_armv8-b39476ede8baa276.51shtnl9jrmqr2vu.rcgu.o" "/home/yuanzhiqiu/os/yzqos_armv8/target/aarch64-unknown-none-softfloat/debug/deps/yzqos_armv8-b39476ede8baa276.5a7lwex1qifr7uk6.rcgu.o" "--as-needed" "-L" "/home/yuanzhiqiu/os/yzqos_armv8/target/aarch64-unknown-none-softfloat/debug/deps" "-L" "/home/yuanzhiqiu/os/yzqos_armv8/target/debug/deps" "-L" "/home/yuanzhiqiu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/aarch64-unknown-none-softfloat/lib" "-Bstatic" "/home/yuanzhiqiu/os/yzqos_armv8/target/aarch64-unknown-none-softfloat/debug/deps/librustc_std_workspace_core-1dcf6d93b6d407a2.rlib" "/home/yuanzhiqiu/os/yzqos_armv8/target/aarch64-unknown-none-softfloat/debug/deps/libcore-1bf904a56375861d.rlib" "/home/yuanzhiqiu/os/yzqos_armv8/target/aarch64-unknown-none-softfloat/debug/deps/libcompiler_builtins-4f3ab19918958b56.rlib" "-Bdynamic" "--eh-frame-hdr" "-znoexecstack" "-L" "/home/yuanzhiqiu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/aarch64-unknown-none-softfloat/lib" "-o" "/home/yuanzhiqiu/os/yzqos_armv8/target/aarch64-unknown-none-softfloat/debug/deps/yzqos_armv8-b39476ede8baa276" "--gc-sections"
= note: rust-lld: error: undefined symbol: LD_STACK_PTR
>>> referenced by 5a7lwex1qifr7uk6
>>> /home/yuanzhiqiu/os/yzqos_armv8/target/aarch64-unknown-none-softfloat/debug/deps/yzqos_armv8-b39476ede8baa276.5a7lwex1qifr7uk6.rcgu.o:(.text.boot+0x18)

error: could not compile yzqos_armv8 due to previous error

修改编译命令但不新增.cargo/config.toml文件的话报错如下：

cargo build --target aarch64-unknown-none-softfloat.json
Compiling yzqos_armv8 v0.1.0 (/home/yuanzhiqiu/os/yzqos_armv8)
warning: target json file contains unused fields: abi-blacklist

error[E0461]: couldn't find crate core with expected target triple aarch64-unknown-none-softfloat-5103292167306961306
|
= note: the following crate versions were found:
crate core, target triple aarch64-unknown-none-softfloat: /home/yuanzhiqiu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/aarch64-unknown-none-softfloat/lib/libcore-ac4407b588a64e53.rlib

warning: yzqos_armv8 (bin "yzqos_armv8") generated 1 warning
error: could not compile yzqos_armv8 due to previous error; 1 warning emitted

关于编译命令，想更为方便的话，可以如下配置：

.cargo/config.toml文件中添加内容：

[build]
target = "aarch64-unknown-none-softfloat.json"

则编译命令只需

cargo build