Re: [OE-core] issues with wic creating "multi-partition" images?

["Robert P. J. Day" <rpjday@crashcourse.ca>]

On Thu, 12 Aug 2021, Alexandre Belloni wrote:

> Hello,
>
> On 12/08/2021 05:26:47-0400, Robert P. J. Day wrote:
> >
> >   asking from a position of massive ignorance since i just started
> > digging into wic, but i've been reliably assured that i am going to
> > encounter issues with trying to get wic to create what i choose to
> > call "multi-partition" images, and i just want to know if this is an
> > actual issue.
> >
> >   current wic setup is to create an image which supports what i'll
> > call the "preserve" partition -- distinct partition to hold
> > non-upgradeable content; factory default firmware, non-volatile S/W
> > config settings, that sort of thing, that is meant to be preserved
> > across software upgrades. nothing unusual about this, strikes me as
> > pretty standard.
> >
> >   now, any recipe in the current build is allowed to contribute its
> > own preserve data by adding it to a top-level "/preserve" directory.
> > that directory is added to the content of the base package:
> >
> >   FILES_${PN} += "/preserve"
> >
> > and in the end, the wic image is responsible for taking everything
> > under /preserve in the final rootfs and installing it in the preserve
> > partition, wholly separate from however it installs the remainder of
> > the rootfs.
> >
> >   does wic have a problem with doing this? it seems so straightforward
> > that i'm having trouble believing wic can't do it. thoughts? or
> > perhaps a link to some reference board or vendor that has a .wks file
> > that does exactly that?
>
> In your wks.in, you can simply do something like that:
>
> part / --source rootfs --fstype=ext4 --label root --exclude-path=preserve/
> part /preserve --source rootfs --rootfs-dir=${IMAGE_ROOTFS}/preserve --fstype=ext4 --label preserve

  that's what i thought, so i'm going back to the current setup to try
to figure out what the originators thought the problem was.

rday

p.s. as i read it, the only distinction between a "wks" and a "wks.in"
file is the need to pre-process variable substitution in the latter,
correct?