SDK upgrade guide

Zephyr 4.0 to Zephyr 4.1: what needs attention

Migratorisk's knowledge base lists 28 documented changes between Zephyr 4.0 and Zephyr 4.1. 27 of them are rated likely to break code, configuration or builds that use them. Below is each change, what a scan also reviews on this path, and how to see which ones apply to your project.

28documented changes

27rated will or likely to break

11review checks on this path

Find which of these affect your firmware

Migratorisk scans your project on your own computer and reports only the changes your code, configuration and build actually touch. Your source code is not uploaded.

python -m pip install migratorisk
migratorisk scan --project ./your-firmware --from zephyr-4.0.0 --to zephyr-4.1.0 --out report.html

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Where the changes are

Hardware description · 17Build settings · 6Application code · 5

What changes between Zephyr 4.0 and Zephyr 4.1

Ordered by impact. Each item names the release that introduced it and links to the official source. A change only matters if your project uses what changed; the scan checks that.

Likely to break

Kconfig options CONFIG_DISABLE_SSBD and 1 more were removed

Build settings · Zephyr 4.1.0 · Source

Kconfigs CONFIG_DISABLE_SSBD and CONFIG_ENABLE_EXTENDED_IBRS have been deprecated since v3.7. These were removed. Use CONFIG_X86_DISABLE_SSBD and CONFIG_X86_ENABLE_EXTENDED_IBRS instead. Covers 2 names.

Likely to break

Kconfig options SB_CONFIG_MCUBOOT_MODE_SWAP_WITHOUT_SCRATCH and 1 more were replaced

Build settings · Zephyr 4.1.0 · Source

The Kconfig SB_CONFIG_MCUBOOT_MODE_SWAP_WITHOUT_SCRATCH has been deprecated and replaced with SB_CONFIG_MCUBOOT_MODE_SWAP_USING_MOVE, applications should be updated to select this new symbol if they were selecting the old symbol. Covers 2 names.

Likely to break

API MGMT_CB_ERROR_RET was removed

Application code · Zephyr 4.1.0 · Source

The deprecated macro MGMT_CB_ERROR_RET has been removed.

Likely to break

API stepper_enable_constant_velocity_mode was renamed

Application code · Zephyr 4.1.0 · Source

Renamed the stepper_enable_constant_velocity_mode function to stepper_run. The function does not take a velocity parameter anymore. Set the desired speed using the stepper_set_microstep_interval function beforehand.

Likely to break

API stepper_set_actual_position was renamed

Application code · Zephyr 4.1.0 · Source

Renamed the stepper_set_actual_position function to stepper_set_reference_position.

Likely to break

API stepper_set_max_velocity was renamed

Application code · Zephyr 4.1.0 · Source

Renamed the stepper_set_max_velocity function to stepper_set_microstep_interval. The function now takes the step interval in nanoseconds. This allows for a more precise control.

Likely to break

API stepper_set_target_position was renamed

Application code · Zephyr 4.1.0 · Source

Renamed the stepper_set_target_position function to stepper_move_to.

Likely to break

CONFIG_BT_CTLR deprecated in favour of HAS_BT_CTLR

Build settings · Zephyr 4.1.0 · Source

Zephyr 4.1 deprecates CONFIG_BT_CTLR; the link layer is now chosen by HCI driver options that select HAS_BT_CTLR. Setting CONFIG_BT_CTLR in prj.conf or a sysbuild image config fails on later releases.

Likely to break