DFU zip is big when including bootloader

[Jesper W.]

I'm using SDK 15.3 and nrfutil version 4.0.0 for generating DFU zip files. 

When I generate a DFU zip file that includes the bootloader the zip files is far to big.

This is my source hex files SD + AP + BL :

297.137 ble_app_buttonless_dfu_s132.hex
423.649 s132_nrf52_6.1.1_softdevice.hex
  66.035 secure_bootloader_ble_s132.hex

nrfutil pkg generate --hw-version 52 --application ble_app_buttonless_dfu_s132.hex  --application-version 0x01 --sd-req 0xB7 --key-file private.pem Tag_sdk153_APv0.0.1.zip

106.325 Tag_sdk153_APv0.0.1.zip

nrfutil pkg generate --hw-version 52 --sd-req 0xB7 --bootloader-version 0x01 --bootloader secure_bootloader_ble_s132.hex --key-file private.pem Tag_sdk153_BLv0.0.1.zip

511.553 Tag_sdk153_BLv0.0.1.zip

Here the generate DFU file explode in size (511KB) compared the original bootloader hex file (66KB) and the same seem to happen whenever the bootloader is part of the generated DFU file. 

765.344 Tag_sdk153_APv0.0.1_SD_BLv0.0.1.zip
489.964 Tag_sdk153_SD_BLv0.0.1.hex
659.362 Tag_sdk153_SD_BLv0.0.1.zip

Can anybody explain this ? and are there anything I can do to shrink the files ?

[Jesper W.]

I seems like the "nfrutil pkg generate" generates a binary for the bootloader alone covering the whole flash area, where most of the binary, up to the bootloader etc. contains 

c3 bf c3 bf c3 bf c3 bf c3 bf c3 bf c3 bf c3 bf c3 bf c3 bf c3 bf c3 bf c3 bf c3 bf c3 bf c3 bf 
c3 bf c3 bf c3 bf c3 bf c3 bf c3 bf c3 bf c3 bf c3 bf c3 bf c3 bf c3 bf c3 bf c3 bf c3 bf c3 bf  

etc. 

so it seem like an failure in the output from nrfutil !!

Any suggestions to solve this problem ?

[Jesper W.]

Found the answer in https://github.com/NordicSemiconductor/pc-nrfutil

When creating update packages of bootloaders compiled from nRF5 SDK 15.3.0 and higher, nrfutil version 5.0.0 must be used. This is because of changes to the bootloader projects in the nRF5 SDK, and if an old nrfutil version is used the size of the generated packages will be too large.

:-)

[AndreasF]

Hi.

I'm glad you figured it out, I have marked your answer as "Verified Answer" on this question.

Best regards,

Andreas