arXiv subjects

Albert Schulz

Publications and source records attributed to Albert Schulz.

2 recordsLinked to original sources

arXiv2026

CTTE: An Open Dual-Protocol RISC-V Trace Encoder for N-Trace and E-Trace

RISC-V standardizes two processor-trace formats, N-Trace and E-Trace, that share a hart-to-encoder instruction trace interface but differ in compression, messages, and framing. To the best of our knowledge, as of August 2026, no publicly available synthesizable N-Trace encoder and no published hardware encoder with both back ends behind a common front end have been reported. We present CTTE (CEDARtools.TraceEncoder), an open SystemVerilog encoder with a protocol-agnostic front end and selectable N-Trace/Nexus or E-Trace back ends. CTTE implements the N-Trace 1.0 program-trace message set in both instruction-trace modes, supports parameterized N-Trace address width, follows the RISC-V Trace Control Interface, and announces output-bandwidth loss before state re-convergence on the evaluated N-Trace path. CTTE has been integrated with six RISC-V cores from five suppliers. We evaluate 64-bit RISC-V systems booting Linux, including a two-hart SMP system, and demonstrate source-side process-context filtering that doubles observation depth for a target process in a fixed buffer. Verification combines instruction-exact round trips, RTL invariants, formal model checking, and machine-judged hardware campaigns with negative controls. With hardware and configuration held constant, workload choice changes trace cost from 0.21 to 4.90 bits per retired instruction. A common front end also enables controlled back-end comparisons while exposing synchronization and transport effects that must be separated from wire-format effects. RTL, register sources, tests, formal properties, decoder extensions, and build scripts are released under CERN-OHL-S-2.0; proprietary integration is available under an Accemic commercial license.

cs.AR↗

arXiv2026

Integration-First Structural Coverage for Embedded Software:Trace-Based Evidence, Hybrid Runtime Analysis, and Cross-Variant Consolidation

Structural coverage is widely used as evidence that testing is complete, yet in embedded projects it is predominantly collected at unit level, simply because that is where instrumentation and observability are inexpensive. This produces a mismatch. The most representative completeness signal would come from integration and system tests executed on the device under test, but classical instrumentation perturbs timing, memory footprint and concurrency behaviour, while purely trace-reconstructed coverage loses reliability for decisions and conditions as soon as the compiler optimizes aggressively. We address this mismatch from both ends. On the process side we describe an integrationfirst coverage strategy that treats integration and system tests as the baseline measurement and drives the residual gaps through an explicit closure loop, so that completeness is established as covered or justified rather than as covered alone. On the technical side we use embedded trace as the observation path and add hybrid runtime analysis (hRA): a minimal, semantics-preserving observability scaffolding that keeps decision and condition boundaries distinguishable in the trace stream of an optimized (-O3) build, while all coverage state and counting remain off-target. This converts object-to-source mapping from a heuristic reconstruction into reviewable evidence and makes branch, condition and MC/DC measurement practical on release-like binaries. Finally we describe Hyper Coverage, a consolidation layer that merges evidence across test levels, test runs, variants and build configurations, and that exposes source lines which remain untested in every relevant variant.

cs.SE↗