I'll add a few more reason to split L1 icache and dcache: 1) limiting pollution, so memcpy doesn't purge L1 of instructions 2) simplifies interface between CPU

I'll add a few more reason to split L1 icache and dcache: 1) limiting pollution, so memcpy doesn't purge L1 of instructions 2) simplifies interface between CPU and icache - only need to support a handful of instruction fetch block sizes CPU actually uses