Alchitry FPGA support?

The guys who made the Mojo v3 FPGA (awesome FPGA for beginners at a low cost around the Spartan 6 XC6SLX9) are coming out with two new boards:

• https://alchitry.com/collections/all/products/alchitry-au
  • Artix 7 XC7A35T-1C - 33,280 logic cells
  • 256MB DDR3 RAM
  • Closed-source toolchain
• https://alchitry.com/collections/all/products/alchitry-cu
  • iCE40-HX8K FPGA - 7680 logic elements
  • No DDR3 :-(
  • Open-source toolchain via icestorm

The Cu is a lot more interesting since it uses the open-source icestorm toolchain.. that would mean a nearly 100% open source implementation of a RISC-V processor on FPGA. I'm not sure the iCE40-HX8K has enough logic elements for a RISC-V core though... and it's lack of DDR is a bit limiting. (nothing says they won't offer a DDR add-on board like on the Mojo though.)

I'm pretty sure the Au has enough space for the RISC-V though... thoughts?

Review the Alchitry Au and Cu product pages linked in the issue, along with the icestorm toolchain mentioned for the Cu. Before work can start, define which board and compatibility behavior are needed and what support would count as complete.