October 2025 monthly performance summary for riscv/riscv-cheri. Delivered comprehensive CHERI RISC-V ISA documentation and associated data updates, consolidating ISA deltas since v0.9.5, adding sections for ISA renames and newly introduced instructions, and clarifying policy on integrity checks for YBLD. Updated the ISA CSV to reflect legacy mnemonics, and improved readability of RV32 YPERMC permissions by aligning rules with encodings. Implemented explicit YSEAL and YUNSEAL warnings to aid correct usage and risk awareness. Fixed a major bug by enforcing integrity checks on YBLD to prevent policy drift and build integrity issues. All changes are in riscv/riscv-cheri and were coordinated with maintainers to enhance adoption, interoperability, and compliance.

September 2025 monthly summary for riscv projects focused on delivering business value through clearer specifications, stronger interoperability, and improved developer experience across riscv/riscv-cheri and riscv/riscv-isa-manual. Key work included extensive documentation and specification clarifications to align encoding naming, C/Zca equivalence, and v1.0 readiness; hypervisor integration improvements and privileged spec enhancements; and expanded encoding support with YSUNSEAL plus bit-range updates on YBNDSWI. UI improvements increased extension discoverability, and code quality efforts standardized formatting, cleaned up the codebase, and removed the hardcoded DDC address to boost configurability and maintainability. In riscv-isa-manual, doc formatting standardization for zcmp/zcmt pages improved readability and consistency.

August 2025 (2025-08) monthly summary for riscv/riscv-cheri: Delivered comprehensive ISA naming and mnemonic modernization, including RVY alignment and misa.y. Implemented encoding-related bug fixes and enhancements to improve correctness and stability, and expanded encoding coverage with pseudoinstructions. Performed extensive codebase cleanup and standardization (massive operand renaming, CSRR page cleanup, C chapter cleanup), and removed the variable XLEN option to simplify builds. Priv spec alignment, consistent YADDRW semantics, and renamed execution modes completed to improve consistency and future-proofing. Overall impact: higher tooling reliability, easier maintenance, faster onboarding for new ISA features, and stronger alignment with the evolving RISC-V ecosystem.

July 2025 (riscv/riscv-cheri) delivered targeted capability and safety improvements that reduce risk, improve reliability, and pave a path for future extensions while delivering clear, business-facing value to teams relying on CHERI features. Key features delivered - Capability addition encodings and future-proofing encodings: Introduced new encodings for capability addition (CADD and CADDI) and clarified ADD/CADD behavior for capability manipulation; reserved encoding space for future extensions. Commits: 42f0b283fe0308688000721f92a5e8266262510c; d636fd745dec50db5955be21b9e32a6c6ec28f0c. Major bugs fixed - CHERI exception handling robustness and integrity checks: Consolidated and improved exception reporting, added integrity checks for ACPERM, and strengthened PCC.ASR handling to prevent security issues and inconsistent behavior. Commits: 8046b5987ca57a01861464485be29814cb1b54a5; 7dd8a4bf617865bb8b221a7f7d006f4f684a7fea; d85efae7c6f7d877778e6bce6d1a743fbaf527fe; c875b2ea1e506a4562832d456c3fb11bfc0957af. Documentation improvements for CHERI features and errors - Comprehensive CHERI documentation improvements covering exception handling, JALR behavior, ASR/PCC permissions, and general clarity across CHERI instructions. Representative commits: 38830e3a59a193b27831d3e39a129eb205db3919; 19212ee36a04e7b0e644d3e6fe539a89e56b2e75; 35ca1950aeaad9c9a4ae89a139f5088cae8f7071; 584e9aa22c16c002a3584917235bd82305ed3d37; 9f702ef711c66451dffaf4a6c95873bd0662652d; c0286028b5692f8fead309a3bcd9fb0ea17c5a05; ca19d41892a43671fa1f1232f1b054d243039524; 8c8d1d96d5c671ca2f09496625e01a7872d4a5ac; 8e9d0812f0ed4d716cf58d4a8d61df44ecca5d54. Overall impact and accomplishments - Security, reliability, and maintainability: stronger protection against misbehavior, more predictable decoding/reporting, and improved developer guidance. This work reduces risk in future CHERI capability evolution and accelerates onboarding for new contributors. Technologies/skills demonstrated - CHERI/RISC-V architecture fundamentals, encoding design, exception handling, security/permisssion checks, and documentation discipline; cross-cutting collaboration across commits to deliver cohesive feature sets and robust fixes.

June 2025 (riscv/riscv-cheri): Focused on strengthening safety semantics, maintainability, and performance through three core initiatives. First, CHERI Architecture Documentation enhancements clarified capability semantics, tagging rules, permissions, and instruction effects, with updates to PCC rules, MTVECC behavior, tags validity, and instruction definitions. Second, CHERI PMA and tag handling enhancements introduced granular tag faulting for invalid tags via CHERI Valid Tag variants, enabling finer fault isolation for loads/stores. Third, RISC-V instruction set simplification removed or deferred branch/jump bounds exception checks, with rationale documented in adoc files to reduce runtime overhead and simplify control flow. Across these efforts, the team also responded to feedback and improved documentation quality (ARC Priv alignment, separation of code/data checks, page tidying) to improve maintainability and review efficiency. The combined work improves safety guarantees, fault isolation, and developer productivity while reducing runtime overhead and integration risk for downstream projects.

Concise monthly summary for May 2025 focusing on CHERI documentation/spec improvements across riscv/riscv-cheri, consolidating thread ID extension into base CHERI, and associated readability and integrity enhancements. Highlights the business value of clarified semantics, improved CSR rules, and reduced risk of misimplementation for developers.

In Apr 2025, delivered CHERI documentation modernization for riscv/riscv-cheri: standardized terminology replacing CLEN with YLEN and validity tag with valid tag; reorganized and clarified instruction pages focusing on bounds, permissions, and special capabilities; updated instruction summaries. Implemented improvements aligned with ARC feedback and code-review learnings, with traceable commits 409c3323f20947218e93f355c63b1c7dbb8907d2 and 0ff842d4ceceedef2ffec9b32e09643c9783613e. Result: clearer docs, reduced ambiguity, and faster onboarding for contributors and users, enabling safer usage and broader adoption of CHERI features.

March 2025 monthly summary for riscv/riscv-cheri focusing on CHERI and unprivileged improvements. Delivered feature work aligning with RISC-V specs, reinforced 2-stage translation semantics, and advanced unprivileged capabilities, complemented by documentation improvements and targeted bug fixes to improve reliability, maintainability, and security posture.

February 2025 (riscv/riscv-cheri): Delivered focused documentation and robustness work to advance CHERI correctness and developer adoption. Key accomplishments include comprehensive documentation improvements and specification clarifications across RV32 and RV64, tightening capability bounds encoding, fault handling behavior, and register semantics, with explicit alignment to recent spec updates (including PTE fault handling and Zilsd/Zclsd extensions). Strengthened robustness by addressing malformed tag clearing on CSP registers and updating the address space sizing from XLEN to MXLEN. Performed release housekeeping with minor version bumps and metadata updates to ensure packaging integrity and traceability (v0.9.4.1). These efforts reduce memory-safety risk, clarify behavior for implementers, and improve maintainability and release quality.

January 2025 monthly summary for riscv/riscv-cheri: Delivered documentation refinements, PTE extension improvements, and exception-handling correctness work, culminating in a formal release. The efforts focused on clarifying behavior, reducing integration risk, and aligning with CHERI specs across multiple execution modes.

December 2024 focused on consolidating CHERI documentation and clarifying guidance across capabilities, CSRs, exceptions, address handling, and instruction access. Delivered a cohesive user-facing update that accompanies the 0.9.2 release, addressing key bug fixes and clarifications in paging and exception handling to reduce misinterpretation and support workload.

November 2024 for riscv/riscv-cheri focused on strengthening security-critical permission handling, clarifying capability semantics, aligning with SAIL compatibility, and enhancing documentation, while advancing release readiness to v0.9.1. Key work highlights included: - ACPERM permission handling in RV32: fixed Zcherilevel ACPERM rules, ensured proper removal and application of permissions, with verification script usage. - CHERI PTE extension enforcement for VM in capability mode: enforce CHERI PTE extension for any VM translation scheme when CHERI base extension is active; describe OS behavior; clarify RV64-only detection. - Capability level reserved entries clarification: clarified that entries 4 and 5 in Quads 2 and 3 are reserved when LVLBITS=1 and in use when LVLBITS=2 in CHERI RISC-V capability levels. - Mstatus CRG field adjustments for SAIL compatibility: remove mstatus.CRG and reinstate with justification, tracking across commits. - Documentation improvements: tables and numeric values — replace hardcoded constants with variables and clarify pcc.M representations for maintainability. - Release version bump to v0.9.1: update Makefile version from v0.9.0 to v0.9.1. Overall, these efforts improved security correctness, clarified CHERI semantics for various LVLBITS configurations, enhanced OS/VM interaction understanding, and improved maintainability and release readiness.

October 2024: Delivered CHERI documentation improvements focusing on fault exceptions, capability levels, and CL semantics. Consolidated user-facing docs, clarified rules for CBLD/SCSS, and refined loads/stores semantics across capability levels. No major code changes this month; primary focus on documentation quality, developer onboarding, and cross-team alignment.