[poky] RFC/RFT Checksums as part of stamp files

[Koen Kooi]

Op 6 jan 2011, om 23:56 heeft Richard Purdie het volgende geschreven:

> We've been working on checksums and sstate for a while, one of the
> pieces we've not put in place so far is using the checksums in the stamp
> files.
> 
> What this would mean in English is the end of PR bumps since when you
> change the recipe, the checksums of the appropriate tasks change and
> everything automatically rebuilds that changed.
> 
> It also means if you change something in the core packaging, everything
> should repackage and so on.
> 
> The final key to enabling this is this commit:
> 
> http://git.pokylinux.org/cgit.cgi/poky-contrib/commit/?h=rpurdie/bitbake-wip&id=b82259b901cae11b0e5715a92a580c9432af52cc
> 
> This hasn't been merged to master yet but we should discuss when this
> change could/should be merged and under what criteria.
> 
> I've only just started testing full builds with the change myself so
> keep that in mind. I'd appreciate testing but the change is still very
> new and likely has bugs to iron out.
> 
> I'm also aware that this idea isn't going to be universally liked,
> particularly I can guess that Koen is going to have concerns about this
> and Angstrom since the lack of PR bumps means package feeds could start
> to suffer.

You saved me from writing a lengthy email about that :) 

> My proposal for dealing with this will be to start having the packaging
> backend take ownership of PE and PR fields. These should be auto
> incremented when the build changes. That in itself is easy enough if you
> have one build area, the tricky bit is where you have multiple build
> sources feeding into a common packages repo like Angstrom.
> 
> For this we're going to need some kind of network service that takes a
> version and provides the PE/PR values back, incrementing them each time
> it sees a new version/checksum.

As a simpler short term solution, can the build "master" write the info to disk (e.g. sqlite) so we can put it in a layer and build "slaves" would just read that back? That we we only need a variable to either read (slaves) or write (master) to that file. It also involves as little as possible network access, since it sits in the metadata git.

regards,

Koen