Session Date/Time: 25 Jul 2024 22:00

bpf

Summary

This meeting covered the current status of BPF standardization efforts within the IETF, particularly focusing on the progress of the ISA document, and plans for future work on Verifier Expectations, BTF (BPF Type Format), PSABI (Platform Specific API), and ELF format specifications. A significant part of the discussion revolved around the prioritization of these work items and the proposed shift to a virtual-only meeting model with ad-hoc in-person meetings when necessary.

Key Discussion Points

ISA Document Completion: The ISA document has successfully progressed through the RFC Editor Queue, marking a significant milestone.
Verifier Expectations Document: Discussed the need for a document outlining the responsibilities of a BPF verifier, including checks for undefined instructions, invalid registers, API contracts, memory safety, and program termination. Existing resources like verifier.rst in the Linux kernel tree and the Prevail academic paper were mentioned as potential sources of text.
BTF (BPF Type Format) Document: Lexi argued for prioritizing the BTF document over the Verifier Expectations document due to its broader applicability (GCC integration, debug format) and the need for standardization to avoid interoperability issues. The existing BTF.RST in the Linux kernel tree was mentioned as a starting point.
PSABI (Platform Specific API) Document: The discussion centered around the scope and nature of the PSABI document. Christoph argued that there should initially only be one PSABI, focusing on interoperability and calling conventions. The discussion involved determining whether PSABI should be "Proposed Standard" or "Informational," a charter change may be required if this is the case.
ELF Format Specification: Dave Thaler presented the current status of the draft on BPF ELF and the challenges related to the e-machine number registration. The discussion covered the historical context of the EMBPF assignment and the questionable state of the relevant registry. It was suggested to reference the Linux kernel elf.h file in the current tree.
Meeting Model: A shift to a virtual-only meeting model was proposed to reduce costs. It was suggested to have regular virtual interim meetings and the possibility of ad-hoc in-person meetings when necessary.

Decisions and Action Items

PSABI Document: Christoph volunteered to draft the PSABI document.
ELF Document: Dave Thaler will look at bringing his existing ELF Internet Draft into the working group.
Chairs: Suresh and David will follow up about scheduling virtual interim meetings, figure out how to solicit agenda items and send a call for help to find someone to work on the BTF document.
BTF Document: Working group to identify someone to champion the BTF standardization effort.

Next Steps

Suresh and David will communicate with the working group about the virtual interim meeting schedule and a call for agenda items.
Christoph to begin drafting the PSABI document.
Dave Thaler to update and resurrect the ELF document.
Working group to try to find a volunteer to edit or champion the BTF document.