July 2026 performance summary focused on deterministic CI artifacts, memory subsystem reliability under virtualization, and RISC-V virtualization correctness. Key outcomes include stable, reproducible SPEC_DIR results for CI artifacts, hardened memory path for virtualization checkpoints, and correctness improvements in nested paging scenarios across XiangShan and NEMU. Key features delivered: - XiangShan: Fixed-Length Commit SHA for CI Artifacts — Introduced fixed-length (9) abbreviated commit SHAs to build SPEC_DIRs, ensuring deterministic directory naming and enabling reuse of existing emulation and checkpoint results across workflow runs (commit 24910190d49b2aa1684f1b817317c976008ee8f2). Major bugs fixed: - XiangShan memory subsystem hardened for virtualization checkpoints — Fixed L1 prefetch and LSQ related issues; added validation to reject stale TLB updates and prevent non-physical store wakeups, removing hangs and difftest errors and ensuring memory consistency during virtualization checkpoints (commit 4cf8b8d4ae343e01dfb54e5ae8febdaeaa9992ae). - NEMU: RISC-V virtualization correctness fixes — Corrected virtual address width handling with MPRV using effective virtual mode for non-instruction accesses, preventing valid Sv48 addresses from being rejected as Sv39 (commit ff009234c146820deacae237b45c6563c709182f), and ignored MXR for implicit G-stage reads during VS page-table walks (commit eddbade47cea7be67380b01e94b1f8cd3b4798c8). Overall impact and accomplishments: - Improved CI reproducibility and faster iteration cycles due to stable SPEC_DIR results. - Increased runtime reliability and correctness for virtualization checkpoint workflows in XiangShan. - Strengthened virtualization semantics and nested paging correctness in NEMU, reducing risk in guest OS deployments and validation tests. Technologies/skills demonstrated: - CI/CD workflow discipline with deterministic artifact management. - Memory subsystem validation and debugging for virtualization scenarios. - RISC-V virtualization semantics, MPRV handling, MXR rules, and nested paging accuracy.

April 2026 monthly summary for OpenXiangShan/difftest: Delivered a critical correctness fix in StoreChecker to properly handle masking for misaligned vector stores, preventing data corruption and improving verification reliability. The change is anchored to commit e6a6076a18a0dd9e283eec25a22435644fa0e4c6 and addresses issue #856, with clear traceability and validation impact.