Session Date/Time: 24 Jul 2023 20:00

bpf

Summary

The first meeting of the BPF working group focused on document logistics, the ISA document, ABI considerations, and the ELF document. Key discussions centered on how the working group will interact with the Linux kernel community, the extension process for the instruction set, and the structure and content of the ABI and ELF documents. The working group tentatively agreed to adopt the existing ISA draft as a working group document and discussed various aspects of future document development and collaboration.

Key Discussion Points

Document Logistics and Collaboration:
- Discussed the current process for generating the ISA document, involving the Linux kernel repository and a separate GitHub repository.
- Addressed how to handle IPR rules and contribution processes, including the roles of editors, authors, and acknowledgements.
- Debated the need for and implementation of an issue tracker for the working group, considering options like GitHub issues, email-based tracking, and the existing IETF tracking system.
ISA Document and Extension Policy:
- Reviewed the working group charter's task to create a clear process for extensions to the instruction set.
- Proposed adding new instructions via extension RFCs rather than revising existing RFCs.
- Debated the location of the instruction set registry, weighing the pros and cons of using IANA versus a file in the Linux kernel tree.
- Discussed different policies for the registry, including first-come-first-served, expert review, and standards action.
- Considered different categories for instruction set entries (historical, permanent, provisional) and their associated policies.
- Discussed two potential options for the IANA registry structure, with a preference emerging for the hierarchical Option 2.
ABI Considerations:
- Defined the scope of an ABI for eBPF, aiming for compatibility across different implementations and operating systems.
- Discussed the importance of separating core ABI elements from platform-specific extensions.
- Addressed the role of the ABI document in helping to close on the ISA document by providing a place to move content not appropriate for the ISA document.
ELF Document:
- Clarified that the ELF document will be an informational document recommending conventions for portable BPF program binaries.
- Addressed the relationship between the ELF document and the BTF document and discussed potential splitting of the documents.
- Highlighted the importance of ELF for cross-platform interoperability and support for multiple tools and compilers.
- Identified different naming conventions for sections within ELF files and discussed the need to document these conventions.

Decisions and Action Items

Tentative Adoption of ISA Draft: The working group expressed support for adopting the Draft Taylor BPF ISA as a starting point for a working group document. The chairs will initiate a formal adoption call on the mailing list.
ISA Editor and Reviewers: Volunteers were solicited to review and edit the ISA document. Interested parties should contact the chairs.
ABI Document Collaboration: Will Hawkins to work with the chairs to move his ABI draft into the correct repository and mailing list for further collaboration.
Action: Determine whether to file the ABI with the Linux kernel.

Next Steps

Adoption Call on Mailing List: The chairs will send out an adoption call for the ISA draft to the mailing list.
ISA Review and Editing: Interested parties should review the ISA draft and volunteer to become editors.
ABI Document Discussion: Continue discussion on the ABI document on the mailing list.
ELF and BTF Document Alignment: Address the question of structure (splitting/combining) of these two documents on the mailing list.