Bootloaders and DFU

Depending on the device, you need to use different bootloader and DFU solutions MCUboot and nRF Secure Immutable Bootloader (NSIB).

See the following table for further comparison.

MCUboot and nRF Secure Immutable Bootloader architecture comparison

Characteristic	MCUboot	nRF Secure Immutable Bootloader
Primary function	Bootloader and DFU	Secure Immutable Bootloader
Customization	Built by users; partitions customized with Kconfig options and DTS. Kconfig and DTS configurable with multi-image builds or sysbuild. Becomes static post-compilation.	Limited; focused on initial boot security.
Slot management	Symmetrical primary and secondary slot style. Primary slot is where the system is executed from (by default). Secondary slot is the destination for the DFU (by default).	Not applicable for firmware updates.
Slot characteristics	Equal primary and secondary slot sizes lead to high memory overhead.	Highly efficient due to immutable design.
Slot definition	Static definition; challenging to change post-deployment.	Fixed and immutable; no post-deployment changes.
Invocation process	Limited customization through metadata.	Authenticated firmware execution; no update mechanism post-boot.
Flash memory layout	Specific allocations for primary and secondary slots.	OTP regions for provisioned data; specific layout for boot and application partitions.

To learn more, refer to the following documentation pages:

Subpages:

• MCUboot and NSIB
  • Quick start guide
  • Enabling a bootloader chain using sysbuild
  • Secure bootloader chain
  • Essential MCUboot configuration items
  • Partitioning device memory
  • Image versions
  • Customizing the bootloader
  • Signature keys
  • Downgrade protection
• Using QSPI XIP split image
  • Requirements
  • Network core image updates
  • Create the Partition Manager static files
  • Create a linker file
  • Set additional Kconfig options
  • Configure sysbuild
  • Relocate code to QSPI flash
  • Set QSPI flash initialization priority
  • Programming with the QSPI XIP split image
  • Firmware updates
  • File descriptions
• MCUmgr Command-line tool
  • Configuring the transport
  • Saving the connection configuration
  • General options
  • List of commands
  • Image management
  • Statistics management
  • Filesystem management
• MCUboot serial recovery
  • Uploading image
  • Implementing serial recovery
  • Using serial recovery mode
• MCUboot image compression
  • Sample
  • Required setup
• Sysbuild-assigned image IDs
  • MCUboot-only images
  • Getting image IDs in an application
  • Image numbers
  • MCUboot update package version
• MCUboot devicetree configuration
  • Bootchain configuration node
  • MCUboot configuration node
  • Enabling bootloader configuration in the application