Rust

对于学习到的一些基础知识，这里不再介绍，着重强调一下用户态这个东西，也就是说U，S，M三种模式

no_std

在linux上面开启一个编译risvc的rust程序也很简单。

• in your project, find the .cargo and go into the file.cargo/config.toml

  • add the following content:

  [build]
  target = "riscv64gc-unknown-none-elf"

• now, go into your main.rs, you will find that there is a error

  • run following commands

  rustup target add riscv64gc-unknown-none-elf

  • then, to fix the error use no_std

  // src/main.rs
  #![no_std]
  #![no_main]
  
  mod lang_items;
  
  fn main(){
  
  }
  
  //src/lang_items.rs
  use core::panic::PanicInfo;
  
  #[panic_handler]
  fn panic(_info: &PanicInfo) -> ! {
      loop {}
  }
  // without this, your project won't go on
  // because you give up std lib
  // in no_std panic_handler is empty
  // which means you must implement it by yourself
  // then you could biuld your project

• debug your project

  • install tools

  cargo install cargo-binutils
  rustup component add llvm-tools-preview

  • DEBUG

  file target/riscv64gc-unknown-none-elf/debug/hello_os
  
  rust-readobj -h target/riscv64gc-unknown-none-elf/debug/hello_os
  
  rust-objdump -S target/riscv64gc-unknown-none-elf/debug/hello_os

learn qemu

qemu-system-riscv64 \
    -machine virt \
    -nographic \
    -bios ../bootloader/rustsbi-qemu.bin \
    -device loader,file=target/riscv64gc-unknown-none-elf/release/os.bin,addr=0x80200000