Immutable bootloader partition setting

RE: Immutable bootloader partition setting

Didrik Rokhaug — Tue, 13 Apr 2021 12:48:10 GMT

I've talked to the developers, and they agree that it is sufficient that the pad region is aligned as long as the image region comes directly behind it.

I will create an internal ticket to have the alignment requirement removed.

RE: Immutable bootloader partition setting

Jasonho — Thu, 08 Apr 2021 23:50:43 GMT

Hi Didrik,

devzone.nordicsemi.com/.../07585.main.c

This is the source code of immutable bootloader.

It only fprotect(disable write) its own flash (b0 slot from 0x0 to 0x8000). It doesn't disable writing in s0 & s1 slot.

And same to mcuboot, it only protect its own flash (0x8200 - 0x14200)

So after 0x14200 is all unprotect area.

Please correct me if I am wrong here.

My question is that why s1_image couldn't be arranged right after the s1_pad (from 0x18200 to 0x28000)?

Why it needs to be 0x1c000 - 0x28000?

Why it needs to have empty space in 0x18200 - 0x1c000

Please find the above image for reference.

Thanks,

Jason

RE: Immutable bootloader partition setting

Didrik Rokhaug — Thu, 08 Apr 2021 15:24:23 GMT

Hi, and sorry for the late answer.

[quote user=""]Why si_image has to be align with end:CONFIG_FPROTECT_BLOCK_SIZE?[/quote]

The immutable bootloader disables writing to the flash pages it and its data resides in.

But, the application must be able to receive and write a new version to flash, the s1 partition must be in unprotected flash.

[quote user=""]Another question is that what is s0_pad & s1_pad? Are they image header info? Can you link me to any source about this.[/quote]

Yes, they are used to hold information about the FW image in the slot.

See https://github.com/nrfconnect/sdk-nrf/blob/master/include/fw_info.h

Best regards,

Didrik