# Delta updates for rootfs/kernel?

**URL:** <https://forum.legato.io/t/delta-updates-for-rootfs-kernel/5064>\
**Category:** Legato Linux distribution (Yocto project)\
**Created:** [March 6, 2020, 5:27pm UTC](https://forum.legato.io/t/delta-updates-for-rootfs-kernel/5064 "2020-03-06T17:27:34Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![dougg3](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.legato.io/dougg3/32/888_2.png) [@dougg3](https://forum.legato.io/u/dougg3)\
**Post date:** [March 6, 2020, 5:27pm UTC](https://forum.legato.io/t/delta-updates-for-rootfs-kernel/5064/1 "2020-03-06T17:27:34Z")

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Hey everyone,

I saw an earlier post on Sierra’s forum about making delta updates that was never resolved:

> **[How to build "delta" binaries for FX30s](https://forum.sierrawireless.com/t/how-to-build-delta-binaries-for-fx30s/15003)**
>
> Hi, I am reposting this from the legato.io forum as I am not getting a response there… Anyone have more information? Hi, I have FX30s in the field that need their applications updated. However I do not want to send the full package. I believe it is...

Where are we with delta update capabilities now? In particular I’m using the WP7702. I see a lot of code in legato that refers to handling delta updates in pa\_fwupdate\_singlesys.c, but I can’t find any tools for generating them or any example files for understanding the format if I wanted to make them myself. Based on the source code it obviously involves bsdiff or imgdiff.

It seems that this capability would be most useful for the rootfs, kernel, and legato partitions. It would sure be nice to update these without requiring a 40 MB update file.

Thanks for any insight!

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**Author:** ![mehdiALL1](https://avatars.discourse-cdn.com/v4/letter/m/f6c823/32.png) [@mehdiALL1](https://forum.legato.io/u/mehdiALL1)\
**Post date:** [July 2, 2020, 8:54am UTC](https://forum.legato.io/t/delta-updates-for-rootfs-kernel/5064/2 "2020-07-02T08:54:56Z")

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Hi … `av-pack` has a bug that you are running into.

Sierra Wireless has a document that describes how to manually do what `av-pack` is supposed to be automating for you (you may have to sign-in to [source.sierrawireless.com](http://source.sierrawireless.com/) to download the PDF): [https://source.sierrawireless.com/resources/airprime/application\_notes\_and\_code\_samples/airprime\_-_wp\_series_-\_airvantage\_fota\_sota\_guidelines/](https://source.sierrawireless.com/resources/airprime/application_notes_and_code_samples/airprime_-_wp_series_-_airvantage_fota_sota_guidelines/)