chore(config/common): remove dead FAST_CREATE_IMAGE variable

[iav]

Summary

• Remove declare -g FAST_CREATE_IMAGE='yes' from config/sources/common.conf. The variable has zero readers in the current tree.

Why this is dead

FAST_CREATE_IMAGE was a real switch once — selecting between dd (slow, safe) and truncate (fast, sparse) for the blank rootfs image. Its life:

When	Commit / PR	What
2020-11-22	3ddd91de7 (#2365)	Introduced as a real switch in lib/functions/image/partitioning.sh (if [[ $FAST_CREATE_IMAGE == yes ]]; then truncate ... else dd ...).
2022-04-05	7b6d9f162 (#3639)	Default flipped to "yes" by adding FAST_CREATE_IMAGE="yes" to the per-arch configs (amd64.conf, armhf.conf, ...).
2022-09-25	72cf555bc (armbian-next)	Consumer removed. partitioning.sh switched to unconditional truncate. Commit subject: bye bye $FAST_CREATE_IMAGE: always use truncate for blank image.
2022-11-06	3e701a857 (#4387, initial RISC-V)	Per-arch declarations dropped during arch-config restructuring, but a fresh export FAST_CREATE_IMAGE='yes' was planted in the new config/sources/common.conf. By this point the consumer had been gone for ~6 weeks.
2023-03-28	62f5fe159	Mechanical shellfmt pass: export ... → declare -g .... No semantic change.

So the line in common.conf is a leftover from a 2022 merge that re-introduced the variable into the new common-config location ~6 weeks after the only code path that read it had been deleted. It has been a no-op ever since.

Why remove it

• A globally-declared *=yes flag with no consumers reads as documentation that the framework supports a "fast image creation" mode users can toggle. It does not — truncate is unconditional.
• Setting FAST_CREATE_IMAGE=no (the previously meaningful override) silently does nothing today.
• The declaration also leaks into config-dump-json/diagnostics output, padding the surface area of "knobs the build supports".

Test plan

• bash lib/tools/shellcheck.sh config/sources/common.conf passes (Congrats, no error's detected in config/sources.)
• After the change, git grep -n FAST_CREATE_IMAGE returns nothing
• No external consumers in armbian/build per GitHub code-search

🤖 Assisted-by: Claude: claude-opus-4-7

[coderabbitai]

📝 Walkthrough

Walkthrough

A single global default configuration variable (FAST_CREATE_IMAGE) is removed from the common configuration file, eliminating its yes default value without a replacement.

Changes

Configuration Variable Removal

Layer / File(s)	Summary
Config Default Removal config/sources/common.conf	Global declaration declare -g FAST_CREATE_IMAGE='yes' is removed, eliminating the default value from the common config file.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

Poem

🐰 A default once stood so bold and bright,
FAST_CREATE_IMAGE with yes—a sight!
But now it's gone, no trace remains,
One line removed from config's chains.
Simpler configs, lighter weight,
We hop along at quickened gait!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'chore(config/common): remove dead FAST_CREATE_IMAGE variable' directly and specifically describes the main change in the PR—removal of an unused variable from the config file.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch chore/remove-fast-create-image

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[github-actions]

✅ This PR has been reviewed and approved — all set for merge!