lowRISC/opentitan
Jul 2025 – Jun 2026
7 Months active
Languages Used
SystemVerilogHjsonYAMLC++HJSONCJSON
Technical Skills
ASIC DevelopmentHardware DesignConfiguration ManagementCI/CDDevOpsYAML scripting
Samuel Riedel
PROFILE
Samuel Riedel
Contributed to the lowRISC/opentitan repository by developing and refining hardware features and configuration flows for RISC-V-based systems, with a focus on the Ibex core. Delivered enhancements such as user-mode performance counter access control and compressed ISA extensions, aligning RTL and documentation with upstream revisions. Addressed build reliability and CI/CD workflow issues by correcting configuration paths and improving automated reporting. Applied SystemVerilog and C programming to implement and verify hardware-software boundaries, register design, and testbench development. Emphasized traceability and maintainability through structured revision history, formal verification, and comprehensive documentation updates, supporting secure, standards-compliant hardware integration and robust development practices.
Overall Statistics
Feature vs Bugs
50%Features
Repository Contributions
11Total
Bugs
4
Commits
11
Features
4
Lines of code
13,274
Activity Months7
Your Network
136 peopleWork History
June 2026
1 Commits • 1 Features
Jun 1, 2026June 2026 monthly summary for lowRISC/opentitan focused on delivering secure, standards-compliant performance counter support and reinforcing upstream alignment. Key feature delivered: - User-mode performance counters access control (mcounteren) in Ibex: implemented gating of performance-counter access to align with RISC-V specifications, enabling safe user-mode access via mcounteren. Included tests for mcounteren functionality and documentation updates. Major bugs fixed: - (Note: The primary change is feature-driven with associated test coverage; no explicit bugs listed beyond integration gaps addressed by upstream update and tests.) Overall impact and accomplishments: - Strengthened security separation between user and privileged modes by enforcing correct mcounteren semantics. - Improved reliability and conformance through added directed tests (including mcounteren lock signal) and updated test suite. - Maintained compliance with upstream changes by updating Ibex integration to revision aae4809a and incorporating the accompanying commit set. Technologies/skills demonstrated: - RISC-V privileged architecture concepts (mcounteren), hardware-software boundary testing, and DV testing. - Upstream integration and vendor/DV workflow (code update from lowRISC/ibex to revision aae4809a; tests, docs, and RTL changes). - Documentation updates to reflect new performance counters and usage guidance.
1 Commits • 1 Features
Jun 1, 2026June 2026 monthly summary for lowRISC/opentitan focused on delivering secure, standards-compliant performance counter support and reinforcing upstream alignment. Key feature delivered: - User-mode performance counters access control (mcounteren) in Ibex: implemented gating of performance-counter access to align with RISC-V specifications, enabling safe user-mode access via mcounteren. Included tests for mcounteren functionality and documentation updates. Major bugs fixed: - (Note: The primary change is feature-driven with associated test coverage; no explicit bugs listed beyond integration gaps addressed by upstream update and tests.) Overall impact and accomplishments: - Strengthened security separation between user and privileged modes by enforcing correct mcounteren semantics. - Improved reliability and conformance through added directed tests (including mcounteren lock signal) and updated test suite. - Maintained compliance with upstream changes by updating Ibex integration to revision aae4809a and incorporating the accompanying commit set. Technologies/skills demonstrated: - RISC-V privileged architecture concepts (mcounteren), hardware-software boundary testing, and DV testing. - Upstream integration and vendor/DV workflow (code update from lowRISC/ibex to revision aae4809a; tests, docs, and RTL changes). - Documentation updates to reflect new performance counters and usage guidance.
June 2026
May 2026
2 Commits • 1 Features
May 1, 2026May 2026: Delivered a targeted improvement to performance counter security and management in lowRISC/opentitan by introducing the mcounteren_writable register for the Ibex core, enabling controlled write access to mcounteren in U-mode. Implemented a dedicated test path verifying set, clear, and lock semantics, including the locking behavior on the Ibex core. The work is supported by two commits, ensuring robust traceability and test coverage across hardware and software boundaries. This reduces risk of unintended counter exposure, improves deterministic behavior of performance counters, and strengthens OpenTitan's CSR-locking model.
May 2026
2 Commits • 1 Features
May 1, 2026May 2026: Delivered a targeted improvement to performance counter security and management in lowRISC/opentitan by introducing the mcounteren_writable register for the Ibex core, enabling controlled write access to mcounteren in U-mode. Implemented a dedicated test path verifying set, clear, and lock semantics, including the locking behavior on the Ibex core. The work is supported by two commits, ensuring robust traceability and test coverage across hardware and software boundaries. This reduces risk of unintended counter exposure, improves deterministic behavior of performance counters, and strengthens OpenTitan's CSR-locking model.
March 2026
1 Commits • 1 Features
Mar 1, 2026March 2026 monthly summary for lowRISC/opentitan focused on strengthening traceability and release readiness for rv_core_ibex through structured revision history and versioning. Key changes align design and verification stages with a formalized revision history, enhancing documentation, audits, and maintainability. No major bugs fixed this month; work emphasizes process improvements and long-term business value. Demonstrated technologies/skills include versioning discipline, commit-signoff practices, and cross-stage collaboration to support auditable releases.
1 Commits • 1 Features
Mar 1, 2026March 2026 monthly summary for lowRISC/opentitan focused on strengthening traceability and release readiness for rv_core_ibex through structured revision history and versioning. Key changes align design and verification stages with a formalized revision history, enhancing documentation, audits, and maintainability. No major bugs fixed this month; work emphasizes process improvements and long-term business value. Demonstrated technologies/skills include versioning discipline, commit-signoff practices, and cross-stage collaboration to support auditable releases.
March 2026
December 2025
3 Commits • 1 Features
Dec 1, 2025Monthly summary for 2025-12: Ibex ISA enhancements delivered to improve code density and performance, plus stability fixes to OpenTitan integration. The work emphasizes upstream compatibility, verification rigor, and maintainability to support faster delivery cycles and lower risk in hardware-software integration.
December 2025
3 Commits • 1 Features
Dec 1, 2025Monthly summary for 2025-12: Ibex ISA enhancements delivered to improve code density and performance, plus stability fixes to OpenTitan integration. The work emphasizes upstream compatibility, verification rigor, and maintainability to support faster delivery cycles and lower risk in hardware-software integration.
October 2025
1 Commits
Oct 1, 2025October 2025 monthly summary for developer work focusing on business value and technical accomplishments in the lowRISC/opentitan repository.
1 Commits
Oct 1, 2025October 2025 monthly summary for developer work focusing on business value and technical accomplishments in the lowRISC/opentitan repository.
October 2025
September 2025
1 Commits
Sep 1, 20252025-09 focused on stabilizing configuration and build reliability for opentitan’s top_darjeeling path. Delivered a critical bug fix to align chip_conn_cfg.hjson with Earl Grey configuration by removing hardcoded paths (conn_csvs_dir and rel_path) and guarding against unset top_chip. This reduces CI/build failures and manual intervention, enabling smoother verification for formal paths across chips.
September 2025
1 Commits
Sep 1, 20252025-09 focused on stabilizing configuration and build reliability for opentitan’s top_darjeeling path. Delivered a critical bug fix to align chip_conn_cfg.hjson with Earl Grey configuration by removing hardcoded paths (conn_csvs_dir and rel_path) and guarding against unset top_chip. This reduces CI/build failures and manual intervention, enabling smoother verification for formal paths across chips.
July 2025
2 Commits
Jul 1, 2025In 2025-07, delivered a crucial bug fix for the Darjeeling ASIC build configuration in the lowRISC/opentitan repository. The changes align technology primitives, remove incorrect generic primitives, and correct the chip codename, ensuring the build uses the correct hardware primitives and that documentation reflects the Darjeeling chip. This reduces production risk, improves CI reliability for the Darjeeling flow, and enhances maintainability.
2 Commits
Jul 1, 2025In 2025-07, delivered a crucial bug fix for the Darjeeling ASIC build configuration in the lowRISC/opentitan repository. The changes align technology primitives, remove incorrect generic primitives, and correct the chip codename, ensuring the build uses the correct hardware primitives and that documentation reflects the Darjeeling chip. This reduces production risk, improves CI reliability for the Darjeeling flow, and enhances maintainability.
July 2025
Activity
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Quality Metrics
Correctness94.6%
Maintainability92.8%
Architecture94.6%
Performance92.8%
AI Usage27.2%
Skills & Technologies
Programming Languages
CC++HJSONHjsonJSONSystemVerilogYAML
Technical Skills
ASIC DevelopmentC programmingCI/CDConfiguration ManagementDevOpsFPGA designHardware DesignRISC-V architectureRTL designSystemVerilogYAML scriptingdigital designdocumentationembedded systemsformal verification
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