Open Source Summit + Embedded Linux Conference + OSPOCon 2021

Smaller computing systems have special needs from the development environment. Limited space and limited processing capability mean that the tooling needs to offer a range of functionality that can be tailored to the target system while allowing mechanisms for leaving unnecessary functionality out of the environment entirely. One area that, surprisingly, hasn't seen much work in the free software world is the C run-time library for 32- and 64- bit microcontrollers. There are C libraries for 8-bit systems, such as Atmel's ATmega series, but ARM and RISC-V embedded systems haven't had a project designed just for them. Picolibc hopes to fill this niche; targeting bare-metal and RTOS systems for 32- and 64- bit processors. This presentation will describe a couple of key features in Picolibc, a stdio implementation that implements precise floating point printf/scanf without using malloc, testing infrastructure validating hundreds of embedded system configurations using QEMU and formal verification effort from the CompCert project at INRIA. Finally, I'll discuss experiences in adding support for Picolibc to numerous free software projects, including FreeRTOS, Zephyr, Crosstool-NG, GCC, QEMU and RIOT.