The hacking continues. Here's one of our 16-core boards and a peripheral board with some RAM on it (there's a version with an Ethernet adapter slapped onto it too - with a proper version of that on the way as well).
The peripheral board is connected (via a hacked cable for pin compatibility) to the bottom-right corner of the 16-core "Swallow" board. From there it can initialise all the cores in the grid and setup the routing tables. The cores are now sitting waiting to be sent programs via X-Link - no more programming over super-slow JTAG.
The JTAG plugged into the Swallow board is just to monitor stuff for debugging. The green wire is just adding a pull-up and the yellow is to allow the peripheral board to issue a reset to the Swallow grid.
The code, which still needs a fair bit of work to be usable, is on Github - https://github.com/stevekerrison/sw_swallow_xlinkboot
- and was built in such a way that means parts of it will be useful for booting other large arrays of XMOS chips in this way (those parts will probably get forked into their own project once the API is stable enough).