Hello World on bare metal, via QEMU emulated ARM machine

Credit:

• https://balau82.wordpress.com/2010/02/28/hello-world-for-bare-metal-arm-using-qemu/
• Rob Landley's talk at the Embedded Linux Conference

Requirements

• qemu-system-arm
• arm toolchain
  • He mentions this
  • I just apt installed the following ubuntu packages

  binutils-arm-none-eabi/focal 2.34-4ubuntu1+13ubuntu1 amd64
    GNU assembler, linker and binary utilities for ARM Cortex-R/M processors
  
  gcc-arm-none-eabi/focal 15:9-2019-q4-0ubuntu1 amd64
    GCC cross compiler for ARM Cortex-R/M processors