substrate-kernels v6.12.91 (linux 6.12.91)

substrate-kernels v6.12.91 — the pre-flattened .kernel bundles for substrate,
built from the pinned linux 6.12.91 (sha256 0ff2ab9e169f9f1948557471fbb450d3018f8c5b77caf288e1a3982582597969).

Artifacts:

• linux-6.12.91-base-x86_64.kernel / linux-6.12.91-base-aarch64.kernel
  — the production guest kernel (monolithic, virtio-only, no tracing).
• linux-6.12.91-debug-x86_64.kernel / linux-6.12.91-debug-aarch64.kernel
  — same kernel + ftrace, kprobes, BPF tracing, BTF, DWARF5, kgdb (ADR 0013).
• SHA256SUMS — checksums for all four bundles.

Builds are byte-reproducible, so each bundle's sha256 is a stable content
identity. Also published to Cloudflare R2, served at
https://kernels.substrate.so/linux-6.12.91-base-x86_64.kernel
(and the matching debug/aarch64 bundles + linux-6.12.91-SHA256SUMS).