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 # riscv64i `#[no_std]` Linux user space example
 
-This repository serves as reference to my later self as starting point for
-`#[no_std]` rust code and to document some cargo configurations.
+This repository serves to my later self as reference to document some
+`#[no_std]` and inline assembly features as well as cargo configurations.
 
-It builds a riscv64i Linux user space binary which invokes some syscalls
+It builds a `riscv64i` Linux user space binary which invokes some syscalls
 according to the Linux [syscall(2)
 ABI](https://man7.org/linux/man-pages/man2/syscall.2.html) for riscv.
 
-When running `cargo run` the binary will be executed using the QEMU riscv user
-space emulator as configured in [.cargo/config](.cargo/config).
+```txt
+Arch/ABI    Instruction           System  Ret  Ret  Error    Notes
+                                  call #  val  val2
+───────────────────────────────────────────────────────────────────
+riscv       ecall                 a7      a0   a1   -
+
+Arch/ABI      arg1  arg2  arg3  arg4  arg5  arg6  arg7  Notes
+──────────────────────────────────────────────────────────────
+riscv         a0    a1    a2    a3    a4    a5    -
+```
+The syscalls are implemented in [lib.rs](src/lib.rs).
+
+When building, cargo runs the [build.rs](build.rs) script before building the
+crate itself, which in this case generates some rust code for the syscall numbers from the riscv C headers.
+
+The binary can be automatically run in the QEMU user space emulator by with `cargo run`, this is because the `runner` is specified in [.cargo/config](.cargo/config).
 
 ## Requirements
-To run this example the QEMU riscv64 user space emulator (`qemu-riscv64`) is
-required.
+- `riscv64-linux-gnu-gcc` toolchain
+- `rustup target add riscv64imac-unknown-none-elf` rust target
+- `qemu-riscv64` QEMU userspace emulator