[yocto] software updates on Yocto based systems with limited connectivity

[Andrea Galbusera]

Hi all,

I've recently been faced the need to support an upgrade path for a system
designed with Yocto. The format for packages is currently ipk.

While the system was under development, I was heavily relying on package
feeds and opkg update/upgrade based upgrades. However, once deployed, this
device will have very limited to no connection to the network. Having the
upgrades deployed by an http feed seems to be a no-option here. Also, every
update should be better delivered in a single file for convenience.

My first approach to the problem, which I'm currently experimenting with,
is to find a suitable way to deliver onto the device whatever is required
to keep going with the opkg update/upgrade logic.
Basically, I'm trying to give the device a filesystem based feed. This can
be deployed as a self-extracting script whose main purpose is to deliver
the usual feed content and to provide a shell script running the usual opkg
update/upgrade recipe. Such an approach would meet the requirement of
delivering a single file, i.e. by uploading it to the system's web
interface.

Now, the most challenging issue I see in moving this solution from an
experimental to a real-world one is that upgrades should be as small as
possible for the sake of efficiency. This will probably involve generating
some sort of "differential" package feed, say between two know hashes of
the system project's metadata. This would allow to only deliver the
required packages: basically those that need to be upgraded, any possibly
changed dependency and, maybe, any additional package that might be
required to instal during the update.

Here comes the question. Is there any effort for solving this or similar
issues, which I guess are not so uncommon in production environments with
limited connectivity? Since I'm not aware of any, I might be completely out
of luck with the described approach.

If you have any experience to share in delivering in-field updates, I'd be
very pleased to learn from your comments or suggestions.

Regards,
Andrea
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.yoctoproject.org/pipermail/yocto/attachments/20130327/70470365/attachment.html>