[OE-core] Wic and "live" images

[Ed Bartosh]

On Mon, May 23, 2016 at 08:13:28AM -0400, Ian Geiser wrote:
>  > On Thu, May 19, 2016 at 05:52:45AM -0400, Ian Geiser wrote: 
>  > > Greetings, I am trying to learn "wic" and have been confused as how to create a "live" style image.  I am following "http://www.yoctoproject.org/docs/1.5.2/dev-manual/dev-manual.html#creating-partitioned-images" but am getting confused on the target to use to create the a file system that has a single squashfs file containing my root file system.   
>  > >  
>  > > My desired partition layout is as follows: 
>  > >       40MiB                 40MiB               300MiB 
>  > > +--------------------+-----------------+-----------------------------+ 
>  > > |      BOOT (esp)    |    DATA (fat)   |          ROOT (live)        |   
>  > > +--------------------+-----------------+-----------------------------+ 
>  > >  
>  > > BOOT - efi boot partition with kernel and initramfs 
>  > > DATA - generic fat filesystem to hold configuration files 
>  > > ROOT - an ext4 filesystem that contains a single os.img, which is a squashfs file. 
>  > >  
>  > > I have ROOT and DATA figured out but I am at a loss as how to generate the os.img file and copy it into ROOT.  If I generate the os.img file with bitbake and then use the "-r" option to manually supply a directory structure it works, but I would rather have it done from a wks file for automation reasons. 
>  > >  
>  > > Any hints? 
>  > I'd suggest to use wic image type and generate your image by bitbake. 
>  > You can find example wic-image-minimal.bb and wic-image-minimal.wks in ../meta-selftest/recipes-test/images/ 
>  >  
> This is where I started.  I was able to make it work but not with my configuration above.  It looks like I can use a type of "fsimage" for my "ROOT" partition, but I have not been able to figure out the syntax there yet.  For "BOOT" I am at a complete loss.  In theory "bootimg-efi" but there doesn't seem to be a way to provide an initramfs.

How about creating recipe to prepare content or your boot partition and then using --source rootfs --rootfs-dir=<your recipe> ?
This is much more generic way of creating partitioned images from my
point of view. Image recipes should take care of content and wic takes care of
putting that content into partitions according to the partitioning
scheme described in .wks

Does it make sense for you?

> 
>  > You can probably do the same by using wic plugins, but I'd not suggest 
>  > to go this way. Using wic image type is simpler, more consistent, easier to do and provides higher level of automation. 
> 
> Is using the wic image type and a plugin mutually exclusive?
No, not at all. However, I personally found the way I described above
more consistent, flexible and easy to implement and maintain.

--
Regards,
Ed