Re: [GIT PULL] kdbus for 4.1-rc1

Greg Kroah-Hartman
2015-04-15T09:20:47Z

On Wed, Apr 15, 2015 at 11:00:50AM +0200, Richard Weinberger wrote:
> Am 15.04.2015 um 10:48 schrieb Greg Kroah-Hartman:
> > On Wed, Apr 15, 2015 at 08:54:07AM +0200, Richard Weinberger wrote:
> >> On Wed, Apr 15, 2015 at 3:36 AM, Andy Lutomirski <luto@amacapital.net> wrote:
> >>>> We had been there before. To paraphrase another... meticulously honorable
> >>>> person, "if you didn't want something relied upon, why have you put it into the
> >>>> kernel?" Said person is on the record as having no problem whatsoever with
> >>>> adding dependencies to the bottom of userland stack.
> >>>
> >>> It appears that, if kdbus is merged, upstream udev may end up requiring it:
> >>>
> >>> http://lists.freedesktop.org/archives/systemd-devel/2014-May/019657.html
> >>
> >> Why so surprised?
> >> kdbus will be a major hard-dependency for every non-trivial userland.
> >> Like cgroups...
> >
> > Maybe because things like cgroups, and kdbus in the future, solves a
> > need that the developers in that area have to solve problems and
> > provide functionality that their users require?
>
> I agree that a high level bus is needed and dbus is not perfect.
> But this does not mean that we need a in-kernel dbus in any case.

So what do you propose to solve the issues presented in my original
email about the usecases that this code addresses?

> > Look, us kernel developers only work on one huge, multithreaded, global
> > state binary. Our experience in multi-application interactions with
> > shared state and permission requirements is usually quite limited. If
> > you don't trust the developers of those programs outside the kernel,
> > don't use them, there are still distros out there that don't require
> > them.
>
> We're all forced to use cgroups, systemd, udev unless we want to have busybox
> as userland. That's a fact.

Is that a problem?

> systemd and its dependencies are not a bad thing per se.
> But we have to be very sure that new hard-dependencies are
> in well shape before we push them into the kernel.

That's fine, and normal, and I expect it. But please provide technical
reasons why the proposal is not acceptable, like Andy has done in this
thread.

thanks,

greg k-h