Concise monthly summary for 2026-01 focusing on features delivered, major fixes, impact, and skills demonstrated across three repositories: OpenXiangShan/XiangShan-doc, riscv/riscv-isa-manual, and OpenXiangShan/NEMU. The month prioritized documentation enhancements and CI workflow improvements, driving faster onboarding, maintainability, and reliable CI processes. Key artifacts include three feature deliveries with dedicated commits and collaboration; no critical bugs fixed in this period; business value includes clearer architectural guidance, streamlined contribution paths, and more stable CI pipelines.

December 2025 monthly summary: Delivered targeted performance, reliability, and automation improvements across the OpenXiangShan ecosystem, with a focus on business value, maintainability, and release discipline. Key features delivered span performance optimization, CI/CD reliability, and scalable release workflows, setting the stage for faster, more reliable product iterations. Key achievements (top 5): - TLBStorage performance optimization in XiangShan: refactored timing path by replacing RegEnable with RegNext to boost throughput and reduce clock gating issues; commit 071b71795ea399ec2507ebcf01f5cfaea7ed32f2. - CI Build Reliability Enhancement: updated GitHub Actions workflow to avoid shallow clones, ensuring full repository history and submodule support during CI builds; commit 7e2d75256cbbbf462367eeb95646c26027fe5d9a. - NEMU CI/CD and release automation improvements: consolidated CI workflows, migrated diff-spike checks to GitHub runners, replaced diff testing with coremark-pro and rvv-bench, and enabled automatic daily releases; commits including 9d6c4e3c0b521097ce236a48159648b181b4e928, 9f7b09b21586aa9b8c880a06d633dc706884736d, 304d1da6a1bae861be9dbf2f6a299cf1c47f383d, and 2b56fbfa2b6279c1873dbb0df876b585cc80f01c. - Ready-to-run binaries management via script and GitHub releases: replaced heavy submodules with a script/config to download ready-to-run binaries from GitHub releases, including automation initialization scripts; commit a33874452b835fd4c357bf0702cb4d3094360e3f. - Compiler optimization flags configurability: added a default empty option for compiler optimization flags to enable build customization; commit c5a061cf852af211c10fdea1cdc71faa04fa2418. Major bugs fixed: RVV vector decoding correctness (RVV 0.3): removed incorrect decodes and duplicated entries across vopm categories to improve decoding accuracy; commits 481de637d5fc5838356caee80a79e56a33754039 and f4ce8f913bdcc91e5674c11e4af63bb1c3595ef3. RISCV Vector Crypto: corrected a variable typo in vsha2c[hl].vv, fixing MessageSchedPlusC operation; commit 7f956f73fac4514932d9efb61c4097fc4ecf093b. Overall impact and accomplishments: Established more reliable CI/CD and release cadence, enhanced hardware performance, and streamlined binary distribution, enabling faster iteration cycles, reduced release toil, and improved testing fidelity across XiangShan, NEMU, and related components. Demonstrated strengths in performance optimization, build engineering, automated release workflows, and cross-repo collaboration. Technologies/skills demonstrated: hardware design/performance tuning (TLBStorage), GitHub Actions CI, release engineering and automation, test benchmarking (coremark-pro, rvv-bench), script-driven packaging, and cross-repo coordination for NEMU and manual documentation updates.

Month: 2025-11 Concise monthly summary focusing on key business value and technical achievements across OpenXiangShan repositories. This period emphasizes correctness in memory subsystem engineering, instrumentation for performance insight, CI reliability, and knowledge dissemination through technical writing. Key deliverables and impact: - Documentation and knowledge sharing: Authored and published four in-depth blog posts explaining memory subsystem architecture and optimization (Memory Access Pipeline, Cache in Modern Processors, Virtual Memory Mechanisms, Atomic Operations). These posts improve onboarding, cross-team understanding, and technical decision-making. Commits include blog entries such as memory-access-827 (#221), #223, #224, and #226 with contributions from Anzooooo and collaborators. - Memory subsystem correctness: Fixed critical TLB address translation behavior in OnlyS2 mode, ensuring gpaddr matches vaddr without unnecessary extension/truncation; reinforces MMU correctness and system stability in 64-to-50/56-bit translation scenarios. (Commit: fix(TLB): gpaddr should be same to vaddr when onlyS2; #5189) - TLB visibility and performance: Integrated PMU events for TLB and wired them into the MemBlock and Frontend to improve performance visibility, enabling data-driven tuning while noting reliability considerations due to non-blocking TLB design. (Commit: feat(pmu): add pmu for TLB; #5205) - Memory management unit (PMM) alignment with MXR: Ensured PMM is disabled during instruction fetch when MXR is effective to align with PMM specifications, reducing translation ambiguities and improving correctness in edge cases. (Commit: fix(MMU): PMM is disabled if MXR is effective; #4997) - CI reliability and workflow improvements: Strengthened CI by introducing init-force for submodule checkout and avoiding shallow clones by fetching full history (depth 0) and enabling submodules; reduces CI flakiness and improves reproducibility. (Commits: ci & build: import make init-force...; ci: avoid shallow clone...; #5211, #5216) - Code quality improvements in NEMU: Minor but important cleanup correcting repeated typos in comments/strings to improve readability and reduce confusion. (Commit: fix: typo "form" in several files; #941) Overall impact: - Reduced risk in memory address translation paths and improved reliability of MMU-related functionality. - Increased ability to observe and tune TLB performance through explicit PMU instrumentation. - More stable and reproducible CI pipelines, accelerating integration and release cycles. - Strengthened documentation base and code readability, supporting faster onboarding and fewer interpretation errors. Technologies/skills demonstrated: - RISC-V memory subsystem concepts (TLB, MXR, PMM, virtual memory) and MMU correctness. - Performance instrumentation (PMU integration) and non-blocking architecture considerations. - CI/CD automation, submodule management, and robust build/test workflows. - Technical writing, cross-repo collaboration, and documentation quality.

October 2025 focused on stabilizing memory-subsystem correctness and enhancing developer enablement across OpenXiangShan/XiangShan and XiangShan-doc. Delivered a critical L1TLB flushing fix for two-stage address translation by disabling address matching during hfence.vvma and sfence.vma when v=1, ensuring proper flush semantics across VS-stage and G-stage entries (commit 007ed3557953cd77812e7e7f70d609c683c49bfa). This patch reduces risk of stale TLB entries at the cost of potential performance trade-offs in two-stage translation scenarios. In parallel, published a comprehensive Out-of-Order memory access guide for XiangShan to clarify memory consistency models, component roles, and practical examples (commit 158639ca15294d8de5a1a7379abefbf6868888a0; co-authored-by: Anzooooo). These efforts improve system reliability, reduce debugging risk, and accelerate developer onboarding and collaboration.

September 2025 highlights: stability improvements, governance enhancements, and documentation-driven quality across the OpenXiangShan ecosystem. Key focus areas included MMU reliability, repository governance, and flexible register access features.

Summary for 2025-08: Delivered critical correctness improvements to the MMU trap handling and NMIE/MPRV semantics in OpenXiangShan/NEMU, with a focus on reliability and business value. The work enhances guest address translation accuracy and trap semantics, resulting in more robust emulation, fewer edge-case failures during hardware error handling, and improved software compatibility for RISC-V workloads. Impact: Reduced risk for teams relying on NEMU for OS validation and driver testing, improved emulator fidelity, and faster debugging cycles due to clearer MMU/NMIE/MPRV behavior. The changes support more stable QA and integration testing across RISC-V software stacks.

July 2025: Documentation-focused month across OpenXiangShan/XiangShan and OpenXiangShan/XiangShan-doc. Delivered consolidated documentation enhancements, clarified licensing terms, and published event materials to improve onboarding, external collaboration, and design reviews. No major bugs fixed this month; focus was on documentation quality and knowledge sharing, enabling faster onboarding and clearer external contributions.

June 2025 performance summary: Delivered targeted improvements across three repositories to strengthen address translation reliability, build tooling, and hypervisor stability. Key deliverables include unifying TLB hit detection and robust gpaddr calculation in XiangShan, enabling Clang as the primary RISC-V toolchain in NEMU with a Clang defconfig, and stabilizing hypervisor exception handling tables in riscv-cheri. Together, these efforts reduce translation errors, accelerate development cycles, and improve runtime correctness for virtualization features. The work demonstrates proficiency in CPU microarchitecture, compiler/toolchain integration, and cross-repo collaboration, translating technical improvements into tangible business value such as fewer mis-translations, faster CI feedback, and more robust platform behavior.

April 2025 performance summary: Reliability, cleanliness, and maintainability improvements across OpenXiangShan projects, with targeted fixes for submodule handling, repository hygiene, and a comprehensive refactor in NEMU. These changes reduce operational friction, improve onboarding, and strengthen the foundation for faster, safer releases.

March 2025: Focused on CI/CD reliability, MMU correctness, and simulation stability. Delivered streamlined artifact generation in XiangShan, fixed regression and MMU translation issues for robust virtualization, and improved NEMU stability by making REPORT_ILLEGAL_INSTR opt-in. Result: fewer flaky builds, more accurate emulation, and faster validation cycles.

Concise monthly summary for Jan 2025 covering OpenXiangShan repos (NEMU, difftest, XiangShan). Emphasizes business value delivered through improved debugging, CI readiness, and documentation governance, as well as environment reliability and code quality improvements.

December 2024 performance summary across OpenXiangShan projects focused on stability, determinism, observability, and performance measurement. Delivered targeted fixes to timing-sensitive PTW/GPF paths, enhanced virtualization timekeeping, upgraded profiling instrumentation, and improved debugging/configurability. These changes reduce runtime risk in production, improve reproducibility for performance analysis, and accelerate readiness for NEMU-related deployments.

November 2024: Focused on correctness, reliability, and CI efficiency across OpenXiangShan projects. Key outcomes include corrected instruction fetch exception handling in XiangShan, CI optimization via gitignore hygiene, accurate Sv48x4 GVPNi address calculation in NEMU, strengthened instruction tracing under PERF_OPT, and aligned difftest interrupt handling with spike/difftest changes.

September 2024 focused on stabilizing and extending CSR and memory-access behavior in OpenXiangShan/riscv-isa-sim. Delivered configurable misaligned memory access to improve Spike compatibility, added Zicntr CSR time handling, and fixed key CSR/trap defects to enhance fidelity and stability. The work reduced crash surfaces, eliminated redundant CSR initializations, and aligned trap semantics with Spike expectations, enabling more reliable simulation and easier integration with Spike and Rocket-chip stacks.

August 2024 monthly summary for OpenXiangShan/riscv-isa-sim: Delivered a GitHub Actions-based CI workflow to automate Spike-So builds, improving CI reliability and speeding up feedback for changes in the RISCV ISA simulator. No major bugs reported this month. Impact includes reduced manual build effort, faster validation, and stronger release confidence. Technologies demonstrated include GitHub Actions, CI/CD automation, and Spike-So integration within the OpenXiangShan workflow.

April 2024 monthly summary for OpenXiangShan/riscv-isa-sim: Implemented configurable support for RVV (Vector) and RVH (Hyper-extended) in the RISCV ISA simulator with a default difftest setup to exercise H-ext features. The changes enhance verification coverage, configurability, and future-proof the simulator against evolving vector/hyper-extension workloads.

December 2023: Strengthened the difftest framework for virtualization testing and improved PMP reliability. Delivered RVH support (RVH CSRs and updated register handling) and fixed a PMP CSR access non-trap issue in the 16–63 range, adding maximum PMP entries configuration and updating the processor state to support it. Result: more accurate virtualization testing, scalable PMP configuration, and reduced risk in hypervisor scenarios.