docs(readme): add guest/host kernel support matrix — closes #244#245
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@hty993 (#244) flagged that there's no documented "supported kernel versions" story, which is a real gap for fleet deployment. Adding a matrix to the Enterprise deployment FAQ. The key clarification the issue was missing: there are *two* kernels, and only the host is the user's variable. - Guest kernel: forkd ships and pins vmlinux-6.1.141. Every snapshot is taken and restored against the same guest kernel, so it's constant across all hosts — it is never the reason a snapshot won't restore elsewhere. - Host kernel: ≥5.7 for live BRANCH (UFFDIO_WRITEPROTECT on memfd), any KVM-capable kernel for basic fork / Diff BRANCH. Tested on 6.14. Deliberately did NOT reproduce the issue's proposed per-version table (6.6.x / 6.8.x "restore broken on 6.8.0-6.8.4" / 6.11.x) — none of those claims are sourceable in this repo or attributed upstream, and a wrong authoritative-looking matrix is worse for fleet operators than a pointer to Firecracker's own kernel-support policy (which owns the host-kernel ABI question and won't drift against a copy here). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Closes #244 (thanks @hty993).
What
Adds a kernel support matrix to the Enterprise deployment FAQ. The framing the issue was missing: two kernels are in play, and only the host is the user's variable.
vmlinux-6.1.141, constantBecause every snapshot is taken and restored against the same shipped guest kernel, the guest side is never the reason a snapshot won't restore on another host. The host kernel is where FC's actual version sensitivity lives — so the matrix points at Firecracker's own kernel-support policy rather than duplicating (and risking drift on) the authoritative host-kernel ABI table.
What I deliberately did NOT add
The issue proposed a table with
6.6.x tested,6.8.x partial — restore broken on 6.8.0–6.8.4 fixed in 6.8.5,6.11.x untested. None of those claims are sourceable in this repo or attributed to an upstream FC issue, and the issue itself marked them as illustrative. A wrong-but-authoritative-looking kernel matrix is an active footgun for the exact fleet-operator audience the issue cares about — so I documented what's actually true and verifiable instead.Test plan