[OE-core] Contents of non-rootfs partitions

[Ulrich Ölmann]

Hi,

On Wed, Nov 23, 2016 at 04:56:56PM +0100, Patrick Ohly wrote:
> On Wed, 2016-11-23 at 15:22 +0200, Ed Bartosh wrote:
> > On Wed, Nov 23, 2016 at 02:08:28PM +0100, Kristian Amlie wrote:
> > > On 23/11/16 13:08, Ed Bartosh wrote:
> > > > On Tue, Nov 22, 2016 at 12:54:52PM +0100, Kristian Amlie wrote:
> > > > [...]
> > > > This can be done by extending existing rootfs plugin. It should be able
> > > > to do 2 things:
> > > > 
> > > > - populate content of one rootfs directory to the partition. We can
> > > >   extend syntax of --rootfs-dir parameter to specify optional directory path to use
> > > > 
> > > > - exclude rootfs directories when populating partitions. I'd propose to
> > > >   introduce --exclude-dirs wks parser option to handle this.
> > > > 
> > > > Example of wks file with proposed new options:
> > > > part /     --source rootfs --rootfs-dir=core-image-minimal       --ondisk sda --fstype=ext4 --label root --align 1024 --exclude-dirs data --exclude-dirs home
> > > > part /data --source rootfs --rootfs-dir=core-image-minimal:/home --ondisk sda --fstype=ext4 --label data --align 1024
> > > > part /home --source rootfs --rootfs-dir=core-image-minimal:/data --ondisk sda --fstype=ext4 --label data --align 1024
> > > > 
> > > > Does this make sense?
> > > 
> > > Looks good. The only thing I would question is that, in the interest of
> > > reducing redundancy, maybe we should omit --exclude-dirs and have wic
> > > figure this out by combining all the entries, since "--exclude-dirs
> > > <dir>" and the corresponding "part <dir>" will almost always come in
> > > pairs. Possibly we could mark the "/" partition with one single
> > > --no-overlapping-dirs to force wic to make this consideration. Or do you
> > > think that's too magical?
> > >
> > Tt's quite implicit from my point of view. However, if people like it we
> > can implement it this way.
> 
> I prefer the explicit --exclude-dirs. It's less surprising and perhaps
> there are usages for having the same content in different partitions
> (redundancy, factory reset, etc.).
> 
> Excluding only the directory content but not the actual directory is
> indeed a good point. I'm a bit undecided. When excluding only the
> directory content, there's no way of building a rootfs without that
> mount point, if that's desired. OTOH, when excluding also the directory,
> the data would have to be staged under a different path in the rootfs
> and the mount point would have to be a separate, empty directory.
> 
> I'm leaning towards excluding the directory content and keeping the
> directory.

what about having both possibilities by leaning against the syntax that rsync
uses to specify if a whole source directory or only it's contents shall be
synced to some destination site (see [1])?

In analogy to this to exclude only the contents of the directory named 'data'
you would use

  --exclude-dirs data/

but to additionally exclude the dir itself as well it would read

  --exclude-dirs data

Best regards
Ulrich

[1] http://man.cx/rsync(1)#heading6
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