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

[Adrian Freihofer <adrian.freihofer@gmail.com>]

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.

Regards,
Adrian

> 
> As a background, for example the Fedora distribution uses dbus-broker
> instead of Freedesktop.org's D-Bus implementation. The following
> excerpts from
> https://fedoraproject.org/wiki/Changes/DbusBrokerAsTheDefaultDbusImplementation
> provide background for their technological decision
> 
>   This change provides a more scalable and more reliable
> implementation in place of the reference implementation.
>   The reference implementation suffers from long-standing issues
> including potential dead-locks and susceptibility to denial of
> service attacks, which the replacement implementation does not.
> 
> and
> 
>   No visible changes in behavior are expected, except for different
> log messages.
>   Any visibly different behavior to `dbus-daemon` should be reported
> as a regression.
>   Ideally, this change should only improve the performance and
> security of the message bus.
> 
> Signed-off-by: Niko Mauno <niko.mauno@vaisala.com>
> ---
>  meta/conf/distro/include/default-providers.inc | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/meta/conf/distro/include/default-providers.inc
> b/meta/conf/distro/include/default-providers.inc
> index d3eefb754b..cebd0400f4 100644
> --- a/meta/conf/distro/include/default-providers.inc
> +++ b/meta/conf/distro/include/default-providers.inc
> @@ -31,6 +31,7 @@ VIRTUAL-RUNTIME_base-utils ?= "busybox"
>  VIRTUAL-RUNTIME_base-utils-hwclock ?= "busybox-hwclock"
>  VIRTUAL-RUNTIME_base-utils-syslog ?= "busybox-syslog"
>  VIRTUAL-RUNTIME_keymaps ?= "keymaps"
> +VIRTUAL-RUNTIME_dbus ?= "dbus"
>  
>  #
>  # Default recipe providers
> 
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