You'll find reference documentation in the GDB Documentation page in the main GDB website. This page collects additional documentation.
* Why Simulation Sucks, written by Michael Frysinger and Robin Getz. A paper on the topic of simulation with a GNU/sim focus. Presented at OSL.
* A Tale of Two Sims, a presentation at LSM by Michael Frysinger, breaking down his experience between QEMU & the GNU/sim and some of the trade-offs.
2. GDB Porting