is Delta DFU supported for nrf52 series or nrf54

[ziv123]

hi Nordic

i am working with nrf52840 and nrf52832 with ncs v2.8.0 

i am also working on nrf54l15 (since nrf54h20 seems to not be fully integrated yet)

i want to know if i can reduce DFU image size by using Delta firmware update mechanism for DFU 

and if it is supported by zephyr and for the devices mentioned ..

if not i would appreciate to learn why ??

i know there is compressed DFU but it requires a lot of resources for the compression libs and algorithms and not very practical in that manner.

hope to read you soon 

best regards

Ziv 

[Turbo J]

Ever ran a bindiff on 2 firmware images with slighly non-trivial changes? The results are often vastly dissimilar.

[ziv123]

i don't want to diff 2 fw binaries, i want to patch relevant changes that can be signed somehow with relevant info of changed module, line numers etc. (just guessing)

if i pass a complete image for diff investigation there is no gain

[Turbo J]

You do realize that DFU works with binary firmware image data and does not care about line numbers whatsoever?

Most modern-ish NRF chips support external QSPI flash chips which are perfect for storing  firmware updates.

Also keep in mind that if you make the bootloader more complex and thus bigger, you will end up with less space for the actual application image in flash.

[ziv123]

it should not necessarily make a bigger bootloader .. and it is not necessarily the bootloader's job to do the patching itself..

furthermore, the idea is to minimize the image size over ble or subG or any other comm protocol to save on transmission or in some cases even to enable update that can not happen for complete image

it is used by nordic for its nrf91 series for its fw update 

you can read on delta DFU here 

https://docs.nordicsemi.com/bundle/ncs-latest/page/nrfxlib/nrf_modem/doc/delta_dfu.html

my guess is that it enable to wrap somehow only the changes inside some relevant informative structure regarding the changes, instead of generating a complete image and send it (which is much much larger then just the changes)

[Vidar Berg]

We only support delta updates for the modem firmware. As Turbo points out, this introduces significant complexities in DFU handling and it also add some limitations. The linker doesn’t need to do much reordering before the image ends up being completely different.

[ziv123]

this is a concept i invented

https://interrupt.memfault.com/blog/ota-delta-updates

and it may be the only solution for FW update for some communication protocols that are not designed for large data transfer.

best regards

Ziv

[Vidar Berg]

Sure, I just thought it was relevant to mention that it comes with some drawbacks as well. I have not checked this myself, so I don't know whether delta updates will work between major SDK and toolchain versions or if you will be forced to stay on the same version.

[ziv123]

hi Vidar

well .. i tried to make a py script with cursor that takes 2 .bin images which represents different app versions and see the diff .. seems like a lot of diff, depending on the change and to your point migrating from ncs 2.5.0 to 2.8.0 changes the whole image so yes there is an issue to solve there

i wonder if there is maybe a way with sysbuild to fix or encapsulate big modules to certain locations in the build  so that way if a module or group of content hasn't changed it will be held all together at one place in memory ?

p.s. i have another thread on coredump issues here https://devzone.nordicsemi.com/f/nordic-q-a/124173/having-issues-with-saving-coredump-to-flash-or-at-all .. it seems like there is much slower response time on devzon than what i was used to, i hope Nordic doesn't consider taking this off it is usually very helpful 

best regards

Ziv

[Vidar Berg]

Hi Ziv,

Yes, this is what I feared. I'm sure there are linker and compiler flags you can experiment with to minimize the changes between builds. I'm not sure it will be enough to enalbe major updates such as this though. As we don't support delta updates, there isn't much I can do but report it as a feature request internally.  

Best regards,

Vidar

[ziv123]

hi Vidar 

Vidar Berg said:

I'm sure there are linker and compiler flags you can experiment with to minimize the changes between builds

can you hint some of the linker and compiler flags you refer to that might be helpful to play with ?