Re: [ptxdist] PTXdist usescases

[Erwin Rol <mailinglists@erwinrol.com>]

Hey Michael,

On Mon, 2018-08-27 at 18:40 +0200, Michael Olbrich wrote:
> On Mon, Aug 13, 2018 at 02:40:14PM +0200, Robert Schwebel wrote:
> > On Mon, Aug 13, 2018 at 02:16:20PM +0200, Erwin Rol wrote:
> > > > Michael Olbrich prototyped a layering system for ptxdist
> > > > we are currently testing the prototype and mol
> > > > will post it here on the mailing list afterwards.
> > > > 

What I am really looking for is to be able to make two (or more)
filesystem images that I can build (and version) independently, and
where the next "layer" does not have to rebuild the previous layer.

For example;

- A rootfs layer that generates a rootfs image, which holds the minimal
setup for the hardware (bash, systemd, etc).

- A qt5fs, which holds QT5 and gui stuff, but that does not need to
build the stuff that is already in the rootfs image (like bash and
systemd).

- A appfs that holds own applications that use QT5 but again without
building qt5fs/rootfs.

On the target those 3 filesystems will than overlay mounted so
everything is at its expected place.

After rootfs and qt5fs are versioned and build, the appfs can be
quickly changed with minimal build time, and it can also be completely
different for example two different projects that use the same base
hardware. Than you just have to version and manage 1 rootfs/qt5fs and 2
appfs projects. 

That is different from the yocto layer system where you build up your
one-and-only rootfs out of different layers. The caching might reduce
build times but the versioning is still a problem.

Also the updating of the target is easier when only a 4MB appfs has to
be distributed than when 250MB rootfs has to be distributed. 

Robert mentioned you where working on some sort of layering system, and
I was hoping I maybe could use that as a base :-)

- Erwin


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