pstorage and flash pages

[RK]

I'm trying to understand how pstorage allocates storage.

PSTORAGE_FLASH_PAGE_SIZE is fixed, that's the actual size of a flash page and thus a basic unit as you can only clear flash in pages, this I understand.

Should the PSTORAGE_DATA_START and PSTORAGE_DATA_END always be on flash page boundaries? It would seem that should be the case. Is that checked?

Should the PSTORAGE_SWAP_ADDR always be an area one flash page long or should it be larger if PSTORAGE_MAX_BLOCK_SIZE is larger than one flash page?

Does every application registered start on a new flash page? ie if the first application registered only registers one block of 4 bytes on a chip with 1024 byte page size will the second application registered start on the next flash page and 'waste' 1020 bytes or will it start on the same flash page as the first application, at the 5th byte of the page?

[Krishna Shingala]

Hi,

Yes, the PSTORAGE_DATA_START and PSTORAGE_DATA_END need to be page aligned. We will improve our documentation to make this clear.

On the PSTORAGE_SWAP_ADDR, we have the limitation of being able to handle on block size of 1 page. And therefore, only one page should be reserved for swap and PSTORAGE_MAX_BLOCK_SIZE should not exceed a page size.

Regards, Krishna

[RK]

Thanks for that - makes sense - however I'm now confused about this question devzone.nordicsemi.com/.../ from last December where the suggestion is to use one block of 4096 bytes and increase the limit for maximum block size. 4096 bytes is 4 flash pages.