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# Boot Assets Spec
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SysOTA uses requires both immutable system images _and_ a separate boot partition. This naturally raises the question on how are boot assets that live outside of the rootfs updated. This specification defines just that.
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## Boot assets
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Boot assets include all the files that participate in the boot process with the exception of the platform firmware. This may include the following:
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- Kernel image copied to the boot partition
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- Device tree files present in the boot partition
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- EFI programs or other files loaded by the platform firmware
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- Configuration files present in the boot partition read either by the platform firmware or by files loaded by the platform firmware
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## Bundling
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In order to allow SysOTA to update boot assets they must be available in the rootfs image. During the existing update process the rootfs image is replaced with a new image.
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Using platform-specific logic, SysOTA will selectively copy and modify boot assets from the rootfs and put them in the boot partition.
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SysOTA expects boot assets to be deposited into the `/usr/lib/sysota/boot-assets` directory.
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To make integration easier, the boot assets placed here are expected to match what is copied to the boot partition by the image compositor.
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Any adaptations required are performed by SysOTA
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### Raspberry Pi
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For the Raspberry Pi, the boot assets contain the usual set of files:
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- `bootcode.bin` file loaded on some platforms
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- `start.elf` and related files (fix-ups, debug, etc) loaded on all platforms
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- `config.txt` file describing boot configuration
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- `overlays/` directory
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- `kernel.img` (as named by `config.txt`) |
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\ No newline at end of file |
