[dm-devel] [PATCH] announcing the dm-update target

[Mikulas Patocka]

On Tue, 23 Nov 2021, David Anderson wrote:

> In our ecosystem, the OTA generation and on-device application process
> has evolved continually, in every release, for over 10 years now. So
> we think it's unlikely that we'll stop making improvements to it. Our
> current roadmap has other changes in the pipeline too. It's not just
> us trying to eek out diminishing returns. Other parts of the system
> change around us, and the OTA system needs to adapt.
> 
> The performance penalty is something we've been working on, and have
> improved a lot since our first iteration. We're currently
> experimenting with io_uring as well.
> 
> Best,
> 
> -David

Hi

I understand that an update format developed over 10 years will have 
better compression ratio than my format developed in 2 months.

I'd be interested in extending dm-update to handle your your update format 
and possibly add some abstraction, so that it can work with multiple 
formats.

You say that you have "COPY" and "XOR" operations.

How do you search for blocks that are similar, so that the "XOR" method is 
benefical for them? How do you make sure that you don't perform the "XOR" 
operation twice, if there's system crash when performing it?

Could it be possible for you to give us two Android images and a program 
that calculates difference between them? So that we could see how well we 
are performing compared to the existing solution.

Mikulas