Robert O'callahan
Software Engineer at Novell, Inc.
Arcata, California, United States
Summary
🤩
Rockstar🎓
Top SchoolRobert O'Callahan is a software engineer with 23 years of experience, formerly a Mozilla distinguished engineer and later at Google DeepMind, now based in Auckland, New Zealand. He combines deep systems-level expertise—having modified Linux kernel and system-library interfaces to advance the rr record-and-replay debugger and to handle CPU PMUs—with strong contributions to debugging and tooling like gimli (DWARF v5) and the octocrab GitHub client in Rust. He has also reshaped web platform APIs through a major rework of the W3C Web Audio API, demonstrating unusual breadth from low-level performance engineering to web standards and full-stack concerns. His work focuses on hard correctness and compatibility problems at the intersection of hardware, OS, and developer tools. That rare blend of kernel tinkering and API design makes him especially effective at building reliable developer-facing infrastructure.
23 years of coding experience
Bachelor's degree, History/Religious Studies, Bachelor's degree, History/Religious Studies at The College of William and Mary
Github Skills (43)
api-doc10
javascript10
c-language10
system-programming10
dwarf10
api-design10
authentication10
user-authentication10
cross-platform10
linux-kernel10
web-audio-api10
api10
javascripts10
github-api10
rust10
Programming languages (14)
Github contributions (5)
rr-debugger/rr
Jan 2013 - Jan 2023
Record and Replay Framework
Role in this project:
Back-end Developer & System Engineer
Back-end Developer & System EngineerContributions:22 releases, 251 reviews, 3609 commits in 10 years 1 month
Contributions summary:Robert contributed to the rr-debugger/rr repository by implementing and maintaining several low-level system functionalities. Their contributions primarily focused on enhancing performance counter capabilities and handling intricacies related to processor-specific performance monitoring units (PMUs). The user also addressed kernel compatibility and potential issues arising from interactions with other system tools or dependencies. This work involved modification of the system level interfaces of the Linux kernel and system library and likely required deep system level knowledge.
replaylinuxperformancerecord-and-replaydebugger
gimli-rs/gimli
Dec 2017 - Jun 2021
A library for reading and writing the DWARF debugging format
Role in this project:Back-end Developer
Back-end DeveloperContributions:20 commits, 12 PRs, 56 comments in 3 years 6 months
Contributions summary:Robert made significant contributions to the `gimli-rs/gimli` repository, a library for reading and writing the DWARF debugging format. They implemented support for DWARF 5 features, specifically for `.debug_rnglists` and `.debug_loclists` sections and added typed-stack DW_OPs. Additionally, they fixed attribute names and improved the library by supporting coercing Sdata to unsigned values and Udata to signed values.
dwarfpe-filerustloggingelf
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