boards: stm: nucleo_h723zg: added flash partition to work with mcuboot

[thomasbouston]

Closes #75425
Add a partition for flash memory as follows:

• boot_partition: 128k
• slot0_partition: 384k
• slot1_partition: 384k
• storage_partition: 128k

[nordicjm]

Partitions will work but are not optimal, assuming sector size is 128KiB and you are using swap using move, slot0 needs 1 sector to move sectors up by and needs 1 sector to hold swap status and flags, thus slot0 is reduced to 384 - 128 - 128 = 128KiB, so as can be seen having 384KiB in the second slot also means 256KiB of that slot can never be used.

[erwango]

Partitions will work but are not optimal, assuming sector size is 128KiB and you are using swap using move, slot0 needs 1 sector to move sectors up by and needs 1 sector to hold swap status and flags, thus slot0 is reduced to 384 - 128 - 128 = 128KiB, so as can be seen having 384KiB in the second slot also means 256KiB of that slot can never be used.

@nordicjm Thanks for the input. Is there a documentation somewhere which explains MCUBoot requirements around partitions vs sectors sizes to help tailoring flash partitions ?

[nordicjm]

Partitions will work but are not optimal, assuming sector size is 128KiB and you are using swap using move, slot0 needs 1 sector to move sectors up by and needs 1 sector to hold swap status and flags, thus slot0 is reduced to 384 - 128 - 128 = 128KiB, so as can be seen having 384KiB in the second slot also means 256KiB of that slot can never be used.

@nordicjm Thanks for the input. Is there a documentation somewhere which explains MCUBoot requirements around partitions vs sectors sizes to help tailoring flash partitions ?

In the upstream documentation yes: https://docs.mcuboot.com/design.html

[d3zd3z]

I consider that you need two sectors reserved to be a bug. There is no particular reason that the status and the extra area can't be in the extra area, but as you've discovered, it apparently doesn't work.

[d3zd3z]

I've created mcu-tools/mcuboot#2052 to track this.

[erwango]

@thomasbouston Following discussion with @nordicjm and @d3zd3z, it's finally better, as more optimized, to re-instantiate the scratch partition. My bad for the initially wrong feedback.
Do you plan to continue this PR ?

[nordicjm]

Swap using scratch makes no sense here at all, you would need to use a sector for scratch, and you would need a sector for the image flags, so you're not gaining anything.

[thomasbouston]

@thomasbouston Following discussion with @nordicjm and @d3zd3z, it's finally better, as more optimized, to re-instantiate the scratch partition. My bad for the initially wrong feedback. Do you plan to continue this PR ?

Hi, I'm sorry but I don't have time to handle it anymore. If you could take care of it, that would be ideal.

[erwango]

Hi, I'm sorry but I don't have time to handle it anymore. If you could take care of it, that would be ideal.

Not sure we'll have time neither. Let's close it, it can be reopened at anytime.