Change build target to `riscv32ia_unknown_none`

Cargo.toml

@@ -38,7 +38,7 @@ simple-filesystem = { git = "https://github.com/wangrunji0408/SimpleFileSystem-R
 bit-allocator = { path = "crate/bit-allocator" }
 ucore-memory = { path = "crate/memory" }
 
-[target.riscv32i-unknown-none.dependencies]
+[target.riscv32-blog_os.dependencies]
 riscv = { path = "crate/riscv" }
 bbl = { path = "crate/bbl" }
 

Makefile

@@ -13,9 +13,6 @@ arch ?= riscv32
 kernel := build/kernel-$(arch).bin
 iso := build/os-$(arch).iso
 target ?= $(arch)-blog_os
-ifeq ($(arch), riscv32)
-target := riscv32i-unknown-none
-endif
 mode ?= debug
 rust_lib := target/$(target)/$(mode)/librust_ucore.a
 

docs/RISCV.md

@@ -7,6 +7,20 @@
 
 具体配置过程详见[Dockerfile](../riscv-env/Dockerfile)
 
+## Rust-RISCV
+
+### 目标指令集：RISCV32IA
+
+target: riscv32ia_unknown_none
+
+由于工具链二进制版本尚未内置`riscv32ia_unknown_none`的target，因此需提供配置文件：`riscv32-blog_os.json`。
+
+为什么要用原子指令扩展？
+
+RustOS依赖的库中，大部分都使用了Rust核心库的原子操作（core::sync::atomic）。
+
+如果目标指令集不支持原子操作，会导致无法编译。
+
 ## BootLoader
 
 参考[bbl-ucore](https://github.com/ring00/bbl-ucore)及后续的[ucore_os_lab for RISCV32](https://github.com/chyyuu/ucore_os_lab/tree/riscv32-priv-1.10)，使用[bbl](https://github.com/riscv/riscv-pk.git)作为BootLoader。

riscv32-blog_os.json

@@ -0,0 +1,30 @@
+{
+  "llvm-target": "riscv32",
+  "data-layout": "e-m:e-p:32:32-i64:64-n32-S128",
+  "target-endian": "little",
+  "target-pointer-width": "32",
+  "target-c-int-width": "32",
+  "os": "none",
+  "arch": "riscv",
+  "cpu": "generic-rv32",
+  "features": "+a",
+  "max-atomic-width": "32",
+  "linker": "ld.lld",
+  "linker-flavor": "ld",
+  "executables": true,
+  "panic-strategy": "abort",
+  "relocation-model": "static",
+  "abi-blacklist": [
+    "cdecl",
+    "stdcall",
+    "fastcall",
+    "vectorcall",
+    "thiscall",
+    "aapcs",
+    "win64",
+    "sysv64",
+    "ptx-kernel",
+    "msp430-interrupt",
+    "x86-interrupt"
+  ]
+}