[danielinux]

Issue #937 points out a problem with small partition (single-block), which also carry the flags in the same block. This case is technically impossible to manage on those devices with very large sector sizes. As workaround, we suggest to implement CUSTOM_PARTITION_TRAILER with a mechanism pointing to separate partitions. In STM32F4 (like the F411 where the issue was reported), sectors '1' and '2' are smaller (16KB) and can be used to offload the partition flags sector using custom trailer functions.

This patch adds:

• Extra checks at compile time, to forbid single-block (or 2-blocks in case of NVM_FLASH_WRITEONCE) partition geometry without the CUSTOM_PARTITION_TRAILER flag
• Custom trailer partitions (carved via linker script mapping) on sectors '1' and '2' when stm32f4 is compiled with the CUSTOM_PARTITION_TRAILER option
• CI regression tests using renode emulated STM32F411 with the CUSTOM_PARTITION_TRAILER option turned on.

[Copilot]

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[wolfSSL-Fenrir-bot]

Fenrir Automated Review — PR #940

Scan targets checked: wolfboot-src, wolfboot-bugs
Not reviewed (no scan target covers them): .github/workflows/test-renode-blackpill-custom-trailer.yml, Makefile, arch.mk, config/examples/stm32f4-small-blocks-uart-update.config, config/examples/stm32f407-discovery.config, config/examples/stm32f411-blackpill.config, docs/flash_partitions.md, hal/stm32f4-trailer.ld, options.mk, tools/config.mk, tools/renode/stm32f4_flash_alias.repl, tools/scripts/renode-test-custom-trailer.sh, tools/unit-tests/Makefile
Coverage: 3 of 7 in-scope changed file(s) opened by the reviewer; not opened: include/wolfboot/wolfboot.h, test-app/startup_arm.c, tools/keytools/sign.c, tools/unit-tests/unit-update-flash.c

Findings: 1
1 finding(s) posted as inline comments (see file-level comments below)

This review was generated automatically by Fenrir. Reported findings require changes before merge.

Review tier: Lite

[wolfSSL-Fenrir-bot]

Fenrir Automated Review — PR #940

Scan targets checked: wolfboot-src, wolfboot-bugs
Not reviewed (no scan target covers them): .github/workflows/test-build-cmake.yml, .github/workflows/test-renode-blackpill-custom-trailer.yml, CMakeLists.txt, CMakePresets.json, Makefile, arch.mk, config/examples/stm32f4-small-blocks-uart-update.config, config/examples/stm32f407-discovery.config, config/examples/stm32f411-blackpill.config, docs/flash_partitions.md, hal/stm32f4-trailer.ld, options.mk, tools/config.mk, tools/renode/stm32f4_flash_alias.repl, tools/scripts/renode-test-custom-trailer.sh, tools/unit-tests/Makefile
Coverage: 1 of 2 in-scope changed file(s) opened by the reviewer; not opened: tools/unit-tests/unit-update-flash.c

Findings: 1
1 finding(s) posted as inline comments (see file-level comments below)

This review was generated automatically by Fenrir. Reported findings require changes before merge.

Review tier: Lite

[wolfSSL-Fenrir-bot]

Fenrir Automated Review — PR #940

Scan targets checked: wolfboot-src, wolfboot-bugs
Not reviewed (no scan target covers them): .github/workflows/test-build-cmake.yml, .github/workflows/test-renode-blackpill-custom-trailer.yml, CMakeLists.txt, CMakePresets.json, Makefile, arch.mk, config/examples/stm32f4-small-blocks-uart-update.config, config/examples/stm32f407-discovery.config, config/examples/stm32f411-blackpill.config, docs/flash_partitions.md, hal/stm32f4-trailer.ld, options.mk, tools/config.mk, tools/renode/stm32f4_flash_alias.repl, tools/scripts/renode-test-custom-trailer.sh, tools/unit-tests/Makefile
Coverage: 1 of 2 in-scope changed file(s) opened by the reviewer; not opened: tools/unit-tests/unit-update-flash.c

Fenrir result: Approved ✅

No new issues found in the changed files.

Advisory only — this automated result does not count as a GitHub approval.

Review tier: Lite

Fenrir's latest completed scan found no issues; clearing the prior automated change request.