1.1. Rationale

Although the GDB project includes a 100 page guide to its internals, that document is aimed primarily at those wishing to develop GDB itself. The document also suffers from three limitations.

It tends to document at a detailed level. Individual functions are described well, but it is hard to get the big picture.
It is incomplete. Many of the most useful sections (for example on frame interpretation) are yet to be written.
Is tends to be out of date. For example the documentation of the UI-Independent output describes a number of functions which no longer exist.

Consequently the engineer faced with their first port of GDB to a new architecture is faced with discovering how GDB works by reading the source code and looking at how other architectures have been ported.

The author of this application note went through that process when porting the OpenRISC 1000 architecture to GDB. This document captures the learning experience, with the intention of helping others.