Merge #14

14: Be more elaborate on toolchain setup (Linux) r=japaric a=andre-richter

I just tested how easy it is to get going from scratch with the current instructions. Turns out it was not that easy and users need to do quite some googling on different errors until they can compile the first time.

Add a more elaborate setup section to resolve that.
Maybe needed for MacOS and Windows too?

Co-authored-by: Andre Richter <[email protected]>

Author: bors[bot]

src/preface.md

@@ -42,13 +42,25 @@ nor is access to a Cortex-M microcontroller needed -- all the examples included
 QEMU. You will, however, need to install the following tools to run and inspect the examples in this
 book:
 
-- [`cargo-binutils`](https://github.com/japaric/cargo-binutils). Install it with `cargo install
-  cargo-binutils`; then run `rustup component add llvm-tools-preview`.
+- [`cargo-binutils`](https://github.com/japaric/cargo-binutils).
 
-- [`cargo-edit`](https://crates.io/crates/cargo-edit). Install it with `cargo install cargo-edit`.
+- [`cargo-edit`](https://crates.io/crates/cargo-edit).
+
+- The `thumbv7m-none-eabi` target.
 
 - QEMU with support for ARM emulation. The `qemu-system-arm` program must be installed on your
   computer. The name may differ for non-Debian based distributions.
 
 - LLDB. GDB with ARM support can also be used, but this book chooses LLDB as it's more likely that
   readers that are not into Cortex-M development have installed LLDB than GDB with ARM support.
+  
+  #### Rust toolchain setup on Linux
+  
+  ```bash
+  rustup default nightly # If you start from scratch, get rustup from https://rustup.rs/
+  rustup target add thumbv7m-none-eabi
+  cargo install cargo-binutils
+  rustup component add llvm-tools-preview
+  sudo apt-get install libssl-dev # For Debian based systems (Ubuntu)
+  cargo install cargo-edit
+  ```