EDB: a GDB-Based Debugger for Ethos

The objective of this work is that of reporting how I developed a user-space debugger, based on GDB, for the Ethos OS—EDB. I am going to introduce the reader to Ethos culture and structure with a particular emphasis on those development tools, their semantics and the kernel internals that more influenced the development of EDB—especially taking into consideration the fact that Ethos is a secure-oriented OS and as such has stricter requirements on authentication and authorization with respect to “traditional” OSs, even when it comes to debugging. Besides Ethos, I am going to introduce GDB, the GNU General Debugger. In doing so, I will focus mainly on GDB Remote Serial Protocol (RSP) which is used by EDB to communicate with GDB remotely. In writing this document I focused on the design choices that guided the development of EDB and the motivations behind them, together with a summary of the most relevant aspects of the implementation.