It's finally here! =) The latest release of gdbstubs (20001007-1627) now includes support for the Hitachi SH-4 processor, and more specifically the Sega Dreamcast platform!
Go on, leech it. You know you want to. =)
I modified the gdb_step function for the SH-2 target to work around a limitation in the 7040-series UBC hardware. I also added a few exception handlers, including one for compiled-in breakpoints.
The latest snapshot of the gdbstubs project is available. It includes support for the SH-2, 68ez328, and cpu32 architectures.