WIP

Cheatsheet for working with C++ in an embedded bare-metal environment.

• Intro
• CPUs
  • ARM
    • ARM Architecture Flags
  • AVR
    • AVR Architecture Flags
  • RISCV
• Hosted vs. Freestanding
• Compilers
  • GCC
  • Clang
  • Language Flags
    • fno-exceptions
    • fno-rtti
  • Optimization Flags
  • Debug Flags
  • Warning Flags
• Assembler
  • Assembler Flags
• Linker
  • Linker Flags
• Tools
  • ar
  • nm
  • objcopy
  • objdump
  • ranlib
  • readelf
  • size
  • strings
  • strip
• Build System
  • Makefile vs. CMake
  • Makefile
  • CMake
• Libraries
• IDE
• Debugging
  • JTAG / SWD
  • GDB
  • QEMU
• Examples

• No MMU (most of the time)

• 32 Bit
• Cortex-M Series

Numbers for Frequency, Flash & RAM where taken from the STM product lineup. Others manufacturers may vary, but will probably have a similar offering.

For the complete list see: GCC manual

• 8 Bit
• Arduino

• 32 Bit
• Open Source ISA

• Headers
• Exceptions
• RTTI

Disable exception handling. See GCC manual for more details.

Disable generation of information about every class with virtual functions for use by the C++ run-time type identification features dynamic_cast and typeid. Can save space if not needed. Mixing code compiled with -frtti with that compiled with -fno-rtti may not work.

When using g++ or clang++ as the linker front end prefix all flags with -Wl. Example: -Wl,--no-undefined

In this section will take a detailed look at a couple of build system, that can be used for embedded bare-metal development. The two most common right now are Makefile or CMake projects, so let's start with those.

First a quick comparison:

• STL
• STL-like
• Boost

• Terminal + Editor
• VS Code
• CLion

# Launches QEMU as an Arduino Uno and printing USART to stdio.
qemu-system-avr -machine uno -bios firmware.elf -serial mon:stdio -nographic

The examples folder contains some basic Makefile & CMake based projects.