RE: Question about partiton alignment

Tim Chao — Tue, 09 Jan 2024 01:45:04 GMT

Got it, thanks

RE: Question about partiton alignment

Didrik Rokhaug — Mon, 08 Jan 2024 16:01:58 GMT

Hi,

As you say, the SPU_FLASH_REGION_SIZE is 32kB on the nRF9160, which means that all boundries between secure and non-secure regions must be on a 32k boundary. Otherwise, when one domain tries to access something in the other domain, you get a fault, or you have to waste space (unless you increase the sizes of the partitions to fill the SPU region).

However, you can have multiple partitions within the same SPU region as long as they belong to the same domain. That means that e.g. the tfm_storage partitions can be placed in the same SPU region, thus only taking 32kB of space, not 80. Below is a pm_static.yml I created for a different project where the tfm_storage partitions have been placed in the same SPU region. You might have to change some of the addresses for it to work in your project, but it should be a good starting point.

tfm_its:
  address: 0xf8000
  size: 0x2000
tfm_otp_nv_counters:
  address: 0xfa000
  size: 0x2000
tfm_ps:
  address: 0xfc000
  size: 0x4000
tfm_storage:
  address: 0xf8000
  span:
  - tfm_ps
  - tfm_its
  - tfm_otp_nv_counters
  size: 0x8000

This also moves the tfm_storage partitions to the end of the flash, which should let you move the non-secure storage partitions after, which in turn will let you increase the mcuboot slots.

Best regards,

Didrik