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Embedded Rust Rust on IoT devices

Lars Gregori SAP Hybris

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Hybris Labs Prototypeshttps://labs.hybris.com/prototype/

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MotivationFunctional IoT (http://fpiot.metasepi.org/):Imagine IoT devices are:

• connected to the internet

• developed in a short time

• storing personal data

• secure

• more intelligence

• inexpensive

Can C design IoT devices like that? No, can’t.

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Agenda

• Rust Overview

• Embedded Rust

• Cross Compiling

• MCU Debugging

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Rust Overview

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rust-lang.org

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rust-lang.org

Rust is a systems programming language that runs blazingly fast, prevents segfaults, and guarantees thread safety.

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Rust Overview

Rust FAQ

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Rust FAQ

• safe, concurrent, practical system language

• “We do not intend to be 100% static, 100% safe, 100% reflective, or too dogmatic in any other sense.”

• Mozilla Servo

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Rust FAQ

• multi-paradigm

• OO

• no garbage collection

• strong influences from the world of functional programming

• built on LLVM

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Rust FAQ

• Cross-Platform

• Android, iOS, …

• Conditional compilation#[cfg(target_os = "macos")]

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Rust Overview

Control & Safety

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Control & Safety

C/C++

Safety

Control

Haskell

Go

Java

Python

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Control & Safety

C/C++

Safety

Control

Haskell

Go

Java

Rust

Python

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Rust Overview

Rust Concepts

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Rust Concepts

• ownership, the key concept

• borrowing, and their associated feature ‘references’

• lifetimes, an advanced concept of borrowing

‘fighting with the borrow checker’

https://doc.rust-lang.org/book/

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letv=vec![1,2,3];letv2=v;//…println!("v[0]is:{}",v[0]);

Ownership

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letv=vec![1,2,3];letv2=v;//…println!("v[0]is:{}",v[0]);

Ownership

ERROR use of moved value: `v`

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letv=vec![1,2,3];letv2=v;take_something(v2);println!("v[0]is:{}",v[0]);

Ownership

ERROR use of moved value: `v`

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letv=1;letv2=v;println!("vis:{}",v);

Ownership

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letv=1;letv2=v;println!("vis:{}",v);

Ownership

Copy Type

OK

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fnfoo(v1:Vec<i32>,v2:Vec<i32>)->(Vec<i32>,Vec<i32>,i32){//dostuffwithv1andv2(v1,v2,42)//handbackownership,andtheresult}

letv1=vec![1,2,3];letv2=vec![1,2,3];let(v1,v2,answer)=foo(v1,v2);

Ownership

@choas#Devoxx #embeddedRust

fnfoo(v1:&Vec<i32>,v2:&Vec<i32>)->i32{//dostuffwithv1andv242//returntheanswer}

letv1=vec![1,2,3];letv2=vec![1,2,3];letanswer=foo(&v1,&v2);//wecanusev1andv2here!

References and Borrowing

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fnfoo(v:&Vec<i32>){v.push(5);}letv=vec![];foo(&v);

References and Borrowing

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fnfoo(v:&Vec<i32>){v.push(5);}letv=vec![];foo(&v);

References and Borrowing

ERROR cannot borrow immutable borrowed content `*v` as mutable

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letmutx=5;{lety=&mutx;*y+=1;}println!("{}",x);

References and Borrowing

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letmutx=5;{lety=&mutx;*y+=1;}println!("{}",x);

References and Borrowing

OK: 6

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letmutx=5;{lety=&mutx;*y+=1;}println!("{}",x);

References and Borrowing

mut{

}

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References and BorrowingThe Rules for borrowing:1. Any borrow must last for a scope no greater than that of the owner.

2. Only one of these kinds of borrows, but not both at the same time:• one or more references (&T) to a resource• exactly one mutable reference (&mut T)

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letmutx=5;

lety=&mutx;*y+=1;

println!("{}",x);

References and Borrowing

ERROR cannot borrow `x` as immutable because it is also borrowed as mutable

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Agenda

• Rust Overview

• Embedded Rust

• Cross Compiling

• MCU Debugging

@choas#Devoxx #embeddedRust

Embedded Rust

@choas#Devoxx #embeddedRust

zinc.rsZinc is an experimental attempt to write an ARM stack that would be similar to CMSIS or mbed in capabilities but would show rust’s best safety features applied to embedded development.

Zinc is mostly assembly-free and completely C-free at the moment.

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STM32 Nucleo-F411RE

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STM32 Nucleo-F411RE

⬅

⬅

Demo

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@choas#Devoxx #embeddedRust

Agenda

• Rust Overview

• Embedded Rust

• Cross Compiling

• MCU Debugging

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Cross-Compiling

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Rustuphttps://www.rustup.rs/

rustup is an installer for the systems programming language Rust

> rustup install nightly-2016-09-17> cd zinc> rustup override set nightly-2016-09-17

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GNU ARM Embedded Toolchainhttps://launchpad.net/gcc-arm-embedded/+download

arm-none-eabi-gccarm-none-eabi-gdb…

eabi = Embedded Application Binary Interface

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Building

cargo build --target=thumbv7em-none-eabi --features mcu_stm32f4

Demo

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@choas#Devoxx #embeddedRust

Agenda

• Rust Overview

• Embedded Rust

• Cross Compiling

• MCU Debugging

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MCU Debugging

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zinc.rs Issue #336 Failing to build example. #336

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>openocd…-cgdb_port3333

>arm-none-eabi-gdb(gdb)targetremote:3333(gdb)file./target/thumbv7em-none-eabi/debug/blink_stm32f4(gdb)breakmain(gdb)continue(gdb)next(gdb)setdelay=1000(gdb)list(gdb)disassemble

Debugging

Demo

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What we’ve seen

• Rust Overview ✔

• Embedded Rust ✔

• Cross Compiling ✔

• MCU Debugging ✔

• Hello World

@choas#Devoxx #embeddedRust

What we’ve seen

• Rust Overview ✔

• Embedded Rust ✔

• Cross Compiling ✔

• MCU Debugging ✔

• blinking Hello World ✔

@choas#Devoxx #embeddedRust

Thank you!