Normalize kernel config hash inputs

[iav]

Summary

Two improvements to kernel artifact hash stability and correctness:

1. Normalize kernel config hash inputs

Problem
The current kernel config hashing makes kernel_config_modification_hash sensitive to option insertion order, which causes two issues:

1. Unstable hash due to insertion order.
   kernel_config_modifying_hashes is populated in hook order; identical final option sets can produce different hashes and artifact versions.

2. Overridden assignments still affect the hash.
   If the same option is set multiple times (e.g. FOO=y then FOO=n), both entries influence the hash even though only the last value takes effect.

Additionally, iteration order for opts_val (assoc array) can be nondeterministic.

Solution

1. Normalize per-group lists (opts_n/opts_y/opts_m).
   Each group is sorted and deduplicated (sort -u). This makes ordering deterministic and removes duplicates without changing behavior (all values in a group are the same: n/y/m).

2. Deterministic ordering for opts_val.
   opts_val keys are sorted before hashing and before applying to .config.

3. Drop overridden assignments when hashing.
   Before computing kernel_config_modification_hash, only the last value per key is kept, so overridden assignments no longer affect versioning.

2. Include toolchain version in kernel artifact hash

Problem
Compiler version (gcc/clang) was not included in the kernel artifact hash. Changing the toolchain would not invalidate the cache, even though different compiler versions produce different binaries.

Solution

• Add KERNEL_COMPILER prefix and compiler version to the hash
• Use only major.minor version (e.g., 13.3), drop patch version to avoid unnecessary cache invalidation
• Falls back to "unknown" if compiler is not available at hash calculation time
• Adds -T${hash} component to artifact version string

Result

• Hash is stable for the same effective option set, regardless of insertion order
• Overridden values no longer affect versioning
• Toolchain changes now properly invalidate kernel cache
• Build behavior and final .config stay the same

Tests

Not added.

Summary by CodeRabbit

• New Features

  • Toolchain version and a short toolchain hash are now included in artifact versioning and debug output for clearer build traceability.

• Improvements

  • Kernel configuration inputs are normalized, sorted and deduplicated before processing for more consistent and stable builds.
  • Hashing now ignores overridden options, producing a stable, reduced hash and clearer reason logs.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[coderabbitai]

📝 Walkthrough

Walkthrough

Stabilizes kernel configuration hashing by reducing duplicate config-change entries to their last occurrence and adding a toolchain-derived hash; also normalizes kernel option lists by sorting and deduplicating opts arrays and opts_val keys before hashing and applying changes.

Changes

Cohort / File(s)	Summary
Kernel hash deduplication & toolchain lib/functions/artifacts/artifact-kernel.sh	Two-pass reduction to keep only the last entry per config key before hashing; compute sha256 of reduced entries (shortened); derive toolchain_version from compiler, add toolchain hash to reasons and common_version_suffix, log toolchain info in debug output.
Kernel option normalization lib/functions/compilation/armbian-kernel.sh	Sort & deduplicate opts_n, opts_y, opts_m into normalized arrays; sort opts_val keys; use normalized arrays/keys for building kernel_config_modifying_hashes and applying .config changes.

Sequence Diagram(s)

(omitted)

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Possibly related PRs

• armbian-kernel: remove inconsistent conditionals #8820: Related modifications to armbian_kernel_config_apply_opts_from_arrays and opts_* handling.

Suggested labels

11

Suggested reviewers

• pyavitz
• teknoid
• leggewie
• igorpecovnik
• chraac
• EvilOlaf

Poem

🐰 I sorted leaves and kept the last,

I hashed the path the old ones passed,
I sniffed the toolchain, gave it name,
A tiny hop to steady frame,
Now builds can dance without the past.

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the primary focus of the changes: normalizing kernel config hash inputs by sorting, deduplicating, and removing overridden entries.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

• 📝 Generate docstrings

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[coderabbitai]

Actionable comments posted: 2

🤖 Fix all issues with AI agents

In `@lib/functions/compilation/armbian-kernel.sh`:
- Around line 520-540: The sort invocations that build
opts_n_norm/opts_y_norm/opts_m_norm and opts_val_keys are locale-dependent and
can yield non-deterministic ordering; update the commands that use sort -u and
sort to force a stable C locale (e.g., prefix with LC_ALL=C) so the arrays
(opts_n_norm, opts_y_norm, opts_m_norm, opts_val_keys) and derived
kernel_config_modifying_hashes are built deterministically across environments.
Ensure you apply this change to every occurrence of sort used for these lists in
the block surrounding opts_n_norm/opts_y_norm/opts_m_norm and opts_val_keys.
- Around line 519-540: The variable opts_val_keys is being created in function
scope (global) and should be local like the other arrays; declare opts_val_keys
as a local variable (e.g., add it to the existing local/declare array line with
opts_n_norm/opts_y_norm/opts_m_norm) so it doesn't leak to global scope, then
keep the subsequent mapfile usage and for-loop over opts_val_keys unchanged;
ensure you reference the same symbol names (opts_val_keys, opts_n_norm,
opts_y_norm, opts_m_norm, kernel_config_modifying_hashes) when updating the
declaration.