Agentic Software Porting: Lessons from the CHERI-PIT
TL;DR
Eight lessons from six months of developing CHERI-PIT, an LLM-agent pipeline that ports C/C++ projects to the memory-safe pure-capability (purecap) ABI of CHERI hardware on Arm Morello, trace a path toward a porting tool that emits reproducible and auditable port recipes.
Abstract
Porting C/C++ software to new hardware is an agent-shaped problem. The source changes stay small, but each one requires scarce expert diagnosis of compiler warnings and hardware faults. This experience paper reports eight lessons from six months of developing CHERI-PIT, a system still under active development. CHERI-PIT is an LLM-agent pipeline that ports C/C++ projects to the memory-safe pure-capability (purecap) ABI of CHERI hardware on Arm Morello. The pipeline has carried 29 upstream projects to reproducible port recipes. Verifier scripts measured zero CHERI faults over each ported project’s test baselines on Morello hardware. The corpus includes a working PostgreSQL server and a complete CRuby interpreter. The lessons fall into three themes: dividing the labor so one pipeline survives project scale, verifying progress mechanically so no claim of success rests on the agent’s own report, and retaining insight gained through porting so the tool grows more capable with each port. Each lesson unfolds as an evolution: what CHERI-PIT initially did, what we observed, and what we changed The lessons together trace a path toward a porting tool that emits reproducible and auditable port recipes.
