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Balau's technical blog on open hardware, free software and security In recent months I played with QEMU emulation of an ARM Versatile Platform Board, making it run bare metal programs, the U-Boot boot-loader and a Linux kernel complete with a Busybox-based file system. I tried to put everything together to emulate a complete boot procedure, but it was not so simple. What follows is a description o

Balau's technical blog on open hardware, free software and security Busybox is a solution for embedded Linux designs that need a compact filesystem: the trick is compiling and linking many system utilities into a single binary that behaves differently based on the name it was used to execute it. A working Linux root filesystem then consists in a small directory tree (/bin, /sbin, /usr/bin, …), a s

Balau's technical blog on open hardware, free software and security Das U-Boot, the universal bootloader, is a crucial piece of software that runs on embedded platforms: its role is to put in place and boot the linux kernel from a hard drive, a flash memory, network or serial line. Here I explain how to try U-Boot on QEMU, and in particular on the emulation of the VersatilePB platform. First, inst

Balau's technical blog on open hardware, free software and security Bare metal programs run without an operating system beneath; coding on bare metal is useful to deeply understand how a hardware architecture works and what happens in the lowest levels of an operating system. I wanted to create a simple example of bare metal program for ARM using free open source tools: RealView Development Suite

Balau's technical blog on open hardware, free software and security Last time I wrote about writing and debugging bare metal ARM software using the CodeSourcery toolchain. Now I want to exploit QEMU’s emulation of a complete system and create the simplest “Hello world!” example. The QEMU emulator supports the VersatilePB platform, that contains an ARM926EJ-S core and, among other peripherals, four