[PATCH 1/2] blspec: allow board files to overwrite config file settings

[Marco Felsch]

Hi Sascha,

On 21-01-19 12:01, Sascha Hauer wrote:
> Hi Marco,
> On Mon, Jan 18, 2021 at 09:48:49PM +0100, Marco Felsch wrote:
> > This commit adds the support to overwrite and/or adapt blspec config
> > files by the following global variables:
> >   - global.blspec.fixup.devicetree
> >   - global.blspec.fixup.initrd
> >   - global.blspec.fixup.options
> >   - global.blspec.fixup.linux
> >   - global.blspec.fixup.devicetree-overlay.
> > 
> > Overwriting blspec-config's shouldn't be the normal case but there are
> > cases where this support is needed. One use-case can be a special
> > handling during update. E.g. the normal boot-flow don't need the initrd
> > but the update-flow uses it because the update system is on the initrd.
> 
> When you have an update system and a regular system on the same
> filesystem then I would expect an additional bootspec entry for the
> update system.

AFAIK, barebox tries to find the correct entry by checking all config
files and loads the first matching config file. Is there a way to
specify an explicite config file?

> > Another use-case could be a dynamic devicetree-overlay handling. E.g.
> > the board code dynamically checks which periphery boards are connected
> > and adds the required overlays dynamically.
> 
> Board code can register overlays already, there's no need for bootspec
> to do that.

But this needs a lot more handling if we boot from nfs or from emmc.
Therefore I utilized the already existing code :)

> Overall overwriting bootspec variables somewhat contradicts the whole
> purpose of bootspec. I don't like that very much, so you'll need very
> good reasons to get this through ;)

Yep, I thought so ;) Therefore I wrote a big warning. It gives you a lot
opportunities to shot yourself in the foot. Therefore I print a warning
if you overwrite a already exisiting config.

Regards,
  Marco