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The SB file is the NXP binary file format for bootable images. The file consists of sections, a sequence of bootloader commands, and data that assists MCU Bootloader in programming the image to target memory. The image data can also be encrypted in the SB file. The file can be downloaded to the target using the MCU Bootloader receive-sb-file command.

https://www.nxp.com/docs/en/user-guide/MBOOTELFTOSBUG.pdf

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i.MX RT bootable image

There are two types of supported boot image:

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