USB Debug Capability (DbC) Support on FreeBSD - Hiroki Sato - EuroBSDcon 2023

Hiroki Sato: USB Debug Capability (DbC) Support on FreeBSD USB Debug Capability (DbC) is a standardized functionality in Host Controller Interface of USB 2.x and 3.x. It is a hardware-level circuitry available as a hidden serial communication channel that can work even with no operating system support and is supposed to be an out-of-band access endpoint for debugging. When a kernel panic occurs, we cannot get debugger access on laptops or consumer-grade motherboards with no physical serial port. USB DbC can be used even in that situation and is greatly helpful for kernel development. This talk covers the technical details of how DbC works, the implementation for FreeBSD, and how to use it. Hiroki Sato: Hiroki Sato is an assistant professor at Tokyo Institute of Technology. His research topics include transistor-level integrated circuit design, analog signal processing, embedded systems, computer network, and software technology in general. He was one of the FreeBSD core team members from 2006 to 2022, has been a FreeBSD Foundation board member since 2008, and has hosted AsiaBSDCon, an international conference on BSD-derived operating systems in Asia, since 2007.