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docs(v0.4): vendor firecracker, document fork strategy#185

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WaylandYang merged 1 commit into
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docs/v0.4-vendored-firecracker
May 28, 2026
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docs(v0.4): vendor firecracker, document fork strategy#185
WaylandYang merged 1 commit into
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docs/v0.4-vendored-firecracker

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Documents the decision to vendor a patched Firecracker for v0.4 (rather than wait on the upstream proposal at firecracker-microvm/firecracker#5912 which is following the standard 30-90 day Feature Request SLA).

New file

docs/VENDORED-FIRECRACKER.md — what / why / where / how:

  • The patched fork: deeplethe/firecracker:forkd-v0.4-mem-backend-shared, one commit (b30f1ba) — the proposal's 33-line diff applied verbatim.
  • Build instructions (tools/devtool build --release).
  • Smoke-check script reference (the /proc/<pid>/maps rw-s vs rw-p test).
  • Rebase plan and what happens if upstream merges (we delete the branch and point back at vanilla).
  • Forward-link to the next three forkd-side phases (5a memfd spawn, 5b default-on, 6 mode=live).

Updated

DESIGN-v0.4-PHASE3-SPIKE.md — flips the status banner from SPIKE to RESOLVED. The original options analysis (A through E) is preserved below the banner as the decision trail.

No code in this PR

Just the strategic decision + how to build the patched binary. The forkd-side integration (Phase 5a — memfd_create in the spawn path) lands separately.

Adds docs/VENDORED-FIRECRACKER.md explaining why forkd vendors a
patched Firecracker (the mem_backend.shared MAP_SHARED option that
v0.4's live-fork needs) and where the fork lives:

  https://github.com/deeplethe/firecracker
  branch: forkd-v0.4-mem-backend-shared

Also flips DESIGN-v0.4-PHASE3-SPIKE.md's status banner from SPIKE
to RESOLVED, noting we picked Option B (vendor) + Option A (upstream
proposal, filed at firecracker-microvm/firecracker#5912). The
vendor path lets Phases 5a-9 proceed regardless of upstream timing.

No code change in this PR — just the strategic decision + how to
build the patched binary.
@WaylandYang WaylandYang merged commit fafb5f9 into main May 28, 2026
2 checks passed
@WaylandYang WaylandYang deleted the docs/v0.4-vendored-firecracker branch May 28, 2026 17:40
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