Re: [OE-core] [PATCH v2 1/6] default-providers: Add VIRTUAL-RUNTIME_dbus variable

[Richard Purdie <richard.purdie@linuxfoundation.org>]

On Sat, 2025-03-29 at 15:02 +0100, Adrian Freihofer via lists.openembedded.org wrote:
> Hi Niko
> 
> Thank you for the patch. It would be nice to have an easy way to switch
> to dbus-broker.
> 
> On Fri, 2025-03-28 at 15:01 +0000, Niko Mauno via
> lists.openembedded.org wrote:
> > The purpose of the new variable is to facilitate oe-core users who
> > wish
> > to use an alternative runtime D-Bus implementation instead of the
> > default Freedesktop.org's dbus, such as dbus-broker, a recipe for
> > which
> > is currently available under
> > meta-openembedded/meta-oe/recipes-core/dbus/
> > 
> > While introducing this facilitation the intent is to preserve the
> > existing functionality, while allowing the user to optionally select
> > an
> > alternative runtime D-Bus implementation by adding the following line
> > e.g. to local.conf file:
> > 
> >   VIRTUAL-RUNTIME_dbus = "dbus-broker"
> 
> Introducing a VIRTUAL-RUNTIME_dbus variable would work. But it requires
> to change all dbus related recipes which are not only in oe-core.
> 
> I'm wondering if using a PREFERRED_RPROVIDER would simplify this.
> https://docs.yoctoproject.org/dev/ref-manual/variables.html#term-PREFERRED_RPROVIDER
> 
> This would probably allow a back and forward compatible implementation
> with changing only the dbus-broker and maybe the dbus recipes plus
> adding something like
>   PREFERRED_RPROVIDER_dbus ?= "dbus"
> or
>   PREFERRED_RPROVIDER_virtual-dbus ?= "dbus"
> to OE-core.

Sadly it doesn't work like that. I regret adding PREFERRED_RPROVIDER as
it doesn't work as people think and only helps under very very rare
circumstances.

Runtime issues are a package manager level problem, not a bitbake one,
unless bitbake is doing variable substitution beforehand, which it only
does with the normal rules.

Cheers,

Richard