Open-source RISC-V development has carried a gap for years: no publicly available synthesizable trace encoder. Every serious SoC team either paid a commercial license or staffed the build. CTTE closes both debts at once -- N-Trace 1.0 and E-Trace behind a single protocol-agnostic SystemVerilog front end. The authors report this is the first on both counts as of August 2026.
The mechanism is straightforward: a common front end that connects to any RISC-V hart-to-encoder instruction trace interface, with back-end selection at build time. CTTE has been integrated with six cores from five suppliers and validated running Linux on a two-hart SMP system. Verification is not shallow -- RTL invariants, formal model checking, instruction-exact round trips, and hardware test campaigns with negative controls. Source-side process-context filtering doubles observation depth for a target process in a fixed buffer. Trace cost measured across workloads runs from 0.21 to 4.90 bits per retired instruction, concrete numbers that let teams budget bandwidth before silicon.
The release is CERN-OHL-S-2.0 for open integration; Accemic licenses the commercial version. Both protocols sharing one front end also enables controlled back-end comparisons that were previously impossible without two separate encoders -- a validation tool that did not exist before this paper.
The practical consequence: teams choosing RISC-V for a new SoC no longer need to budget for a trace encoder as a procurement line item or a sprint. The commercial trace encoder vendors that have been collecting that rent -- a small market, but a friction tax on every RISC-V design that needed serious debug infrastructure -- now have a named open alternative with a formal verification record. Plan accordingly.