[OE-core] Contents of non-rootfs partitions

[Ed Bartosh]

On Thu, Nov 24, 2016 at 08:38:46AM +0100, Kristian Amlie wrote:
> On 24/11/16 07:15, Ulrich Ölmann wrote:
> > 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
> 
> This is creative, but ultimately too unintuitive IMHO. Rsync is the only
> tool which uses this syntax AFAIK, and it's a constant source of
> confusion, especially when mixed with cp or similar commands.
> 

Would this way be less intuitive?
--exclude-path data/*
--exclude-path data

We can go even further with it allowing any level of directories:
--exclude-path data/tmp/*
--exclude-path data/db/tmp
...

--
Regards,
Ed