docs: native snapshot-fork feasibility (GO — extend our libkrun fork)#27
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Code survey of A3S-Lab/libkrun (vendored checkout): vCPU/VM state save+restore already exists as dead code; pause/resume half-wired; TEE guest_memfd is an in-tree precedent for non-anonymous RAM; device serialization missing — but our use case snapshots an IDLE deferred-main template (quiesced queues), shrinking device state to queue registration + the virtio-fs inode map (the one hard item). Native path chosen over a Firecracker/CH second backend (no virtio-fs in FC; no adapter layer; single VMM). 4-phase plan, Phase A = RAM+CPU snapshot/restore with MAP_PRIVATE CoW, go/no-go in ~2 weeks.
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Resolves the backend-selection question from #17: go native in A3S-Lab/libkrun (vendored checkout) instead of adding a Firecracker/CH second VMM.
Survey findings: vCPU/VM save+restore already exists (dead code,
vstate.rs); pause/resume half-wired; TEEguest_memfdis in-tree precedent for file-backed RAM; virtio device serialization is missing — but snapshotting an IDLE deferred-main template (P2) collapses the device problem to queue registration + the virtio-fs inode map.4-phase plan, ~4–6 weeks total; Phase A (memfd RAM +
krun_snapshot/krun_restorewithMAP_PRIVATECoW on a quiesced idle VM) gives a measurable go/no-go in ~2 weeks.