Hello,
I am using a custom board with the STM32WLE5CC in arm mbed, and so far it is working. I am now adding mcuboot, and that needs bootloader support. If I add "bootloader_supported": true it still does not work. My research found out, that I need to add a "sectors" definition in my custom target. If I do that, it builds just fine. The problem is: what values to put there? I used some numbers copied from a random entry on some other STM. I cannot find any documentation explaining, what “sectors” exactly does and what those numbers mean. All I find is answers to some random questions that go like “put these magic numbers in, and it works”.
For now I entered "sectors": [[134217728,2048]], and it kinda makes sense. 134217728 is the flash start address and 2048 the page size - but could you point me to any documentation on this settings - or to values needed for my specific mcu?
The STM32WLE5CC is not listed in the https://github.com/ARMmbed/mbed-os/blob/master/tools/arm_pack_manager/index.json, but you can probably use (or copy and modify) STM32WL55JCIx config.