How to set the values of CONFIG_ROM_END_OFFSET and CONFIG_MCUBOOT_UPDATE_FOOTER_SIZE?

[NamrataGagare-eaton]

Hello All,

I am compiling zephyr 3.6 with my application code with --sysbuild option.
I found CONFIG_ROM_END_OFFSET and CONFIG_MCUBOOT_UPDATE_FOOTER_SIZE which getting assigned to 0x20000 i.e 128K which one sector size of board nucleo_h743zi.
My application size is already including trailer size in image it self so explicitly I don't need FOOTER_SIZE.
I realise the FOOTER_SIZE is reducing flash size allocated to my application images.

I wanted to keep CONFIG_ROM_END_OFFSET and CONFIG_MCUBOOT_UPDATE_FOOTER_SIZE values to be configured through Kconfig or prj.conf, but it is not taking any effect when I set these value in prj.conf or set them using -D in compilation cmd.

I see the value for CONFIG_ROM_END_OFFSET and CONFIG_MCUBOOT_UPDATE_FOOTER_SIZE flags are taken from CMakeCache.list which are calculated below in

mcuboot\boot\zephyr\CMakeLists.txt
set(mcuboot_image_footer_size ${required_size} CACHE INTERNAL "Estimated MCUboot image trailer size" FORCE)
set(mcuboot_image_upgrade_footer_size ${required_upgrade_size} CACHE INTERNAL "Estimated MCUboot up

I kindly request your inputs on above issue.

Thanks in advance.

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[RamPingle-eaton]

@michaeljones It would great if you could help me on this?

[michaeljones]

I can only assume you mean someone else as this means nothing to me.

[RamPingle-eaton]

assume

Oops..
It would very kind of you if you could help me to configure CONFIG_ROM_END_OFFSET and CONFIG_MCUBOOT_UPDATE_FOOTER_SIZE values through Kconfig or prj.conf,

[de-nordic]

Converting to discussion.

[de-nordic]

Check on build output where proj.conf is taken from.
Try pristine rebuild.

[RamPingle-eaton]

In our application, we generate a certificate-signed image, separate it, and append the TLV and mcuboot trailer (footer) to the application image itself using a Python script. This script ensures that the image does not exceed the size of the allocated partition for the application, i.e., the slot0_partition.
Upon observing the CONFIG_MCUBOOT_FOOTER_SIZE and CONFIG__ROM_END_OFFSET, it appears they reduce the size of the slot0_partition. This means we don’t need to consider the footer size separately for the application image.
We are using the CONFIG_BOOT_SWAP_USING_SCRATCH method for firmware upgrades. Is there any way to bypass the CONFIG_MCUBOOT_FOOTER_SIZE and CONFIG__ROM_END_OFFSET through the application? Please let us know.

[nordicjm]

There is an estimate of the tlv data and the size of the mcuboot overhead data plus the extra move sector if you are using swap using move, so I'm not really sure what you are asking. The slot size come from dts and is taken away from this, so the values are correct, if you then add an additional tlv then it is outside the scope of this

[ajarmouni-st]

Use west -v build -p always -b...

[RamPingle-eaton]

There is an estimate of the tlv data and the size of the mcuboot overhead data plus the extra move sector if you are using swap using move, so I'm not really sure what you are asking. The slot size come from dts and is taken away from this, so the values are correct, if you then add an additional tlv then it is outside the scope of this

Thanks for your reply @nordicjm , "I am currently compiling my application using sysbuild. During this process, I noticed that the calculation of footer_size is reducing the size of the application area. It appears that footer_size is used for the code signing of application images. However, in my application, I have already reserved space for code signing in the tlv data area. I am performing code signing using imgtool.py. Therefore, in my application, I don’t require a FOOTER_SIZE calculation or the reservation of space, as my application has already accounted for the tlv data space size.
I am using CONFIG_BOOT_SWAP_USING_SCRATCH" as below

CONFIG_SINGLE_APPLICATION_SLOT:
CONFIG_BOOT_FIRMWARE_LOADER:
CONFIG_BOOT_SWAP_USING_SCRATCH: y
CONFIG_BOOT_SWAP_USING_MOVE:
CONFIG_BOOT_UPGRADE_ONLY:
CONFIG_BOOT_DIRECT_XIP:
CONFIG_BOOT_RAM_LOAD:

As per my understanding CMakeList.txt code (zephyr-v3.6.0\blr_modules\mcuboot\boot\zephyr\CMakeLists.txt) , it says that if you are using any method, it will calculate the "mcuboot_image_footer_size" and "mcuboot_image_upgrade_footer_size".

My question is: How can I ensure that CONFIG_MCUBOOT_FOOTER_SIZE=0 when compiling with sysbuild?

[nordicjm]

You can't, your partition size needs to be correct which includes all the overheads, you can then manually use imgtool after (which doesn't really make much sense because the point in sysbuild is to have things like that automated so it will run imgtool for you)

[RamPingle-eaton]

@de-nordic It would be very kind of you if you could help me to resolve this issue.