Feature: images in image support #2465
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MCUBoot multi image support mode requires each image be procedded individually that requires multiple signature check during boot. If there be 4 image it will require 4 times signature validatation. This feature increase boot time and depend on the project long boot time may not be expected. To provide a solution for this case we propose to - Generate each image as regular - Concatanate them and re generate a main mcuboot image. ------------------------- | Header | ------------------------- | SubImage (optional) | | (Header+Data+Footer) | ------------------------- | SubImage (optional) | | (Header+Data+Footer) | ------------------------- | ..... | ------------------------- | Footer | ------------------------- During boot time if top level image be validated sub image can be just copied to the target location without to recheck them. To provide this feature there will be two commit 1- Provide a script that combine images 2- Update mcuboot source code to process subimages This commit is for mcu-tools#1, in this commit we are adding a script which called as combine_images.py. The usage of the script is: python combine_images.py --config combine_images.yaml --imgtool imgtool --output <outfolder> combine_images.yaml file is added as reference file it need to be updated as per of the project need. Signed-off-by: Sadik Ozer <[email protected]> Signed-off-by: Michael Eskowitz [email protected]
This is source code update to provide images in images feature support. As mentioned in prev commit: MCUBoot multi image support mode requires each image be procedded individually that requires multiple signature check during boot. If there be 4 image it will require 4 times signature validatation. This feature increase boot time and depend on the project long boot time may not be expected. In this commit the loader.c file update to search subimages and copy them in the related load_address. By this solution: - Image update will be handled as requlary - Signature check will be executed for combined image - Boot time will be decreased by eliminating multiple signature check This featue only support for (BOOT_IMAGE_NUMBER == 1 && MCUBOOT_RAM_LOAD) case. Signed-off-by: Sadik Ozer <[email protected]>
@nordicjm thanks for the feedback. While adding this feature we have not change behavior of mcuboot. It is just extended. |
I find this feature useful for bundling multiple images into single envelope so that it can decrease the authentication burden. We may have a discussion on how to infuse it better for the architecture. Yet, adding a hook for tailoring is not the main purpose. The main purpose is to add capability of bundling multiple packs into single image for verification which enhances performance in MCUBoot in general. |
You have taken a mode and completely made up an entirely new container format without any discussion or thought about other MCUboot modes, security, previous version compatibility or design queries or how other supported OS's would implement such a feature notwithstanding a complete lack of documentation. Not to say that such a feature cannot be added, but this is really not at all the correct way to do it |
@nordicjm We tried to add it without changing existing feature as possible as, There might be some items that we missed. We are eager to refactor it as per of your and maintainers feedback and direction to handle it in appropriate way. |
This PR introduce an proposal method that can be used to handle multi image in a single image pack to decrease number of signature check during bootup. By this change multiple images can be loaded/updated on device with one signature check.
Depend on the product this feature might requires to decrease boot up time.
This PR includes:
The feature only support for if (BOOT_IMAGE_NUMBER == 1) and MCUBOOT_RAM_LOAD defined case.
And assume on multicore heterogeneous system the host core which execute MCUBoot FW able to access sub core ITCM/DTCM by just memcpy operation.
The MCUBoot FW after copy them to the target address is going to execute first bootable image.
As an example 3 images can be concatenated as
Simply tested with Zephyr on MAX32690EVKIT
