Re: [Ksummit-discuss] Self nomination

["Rafael J. Wysocki" <rjw@rjwysocki.net>]

On Tuesday, August 02, 2016 10:09:17 AM Linus Walleij wrote:
> On Thu, Jul 28, 2016 at 12:14 PM, Marc Zyngier <marc.zyngier@arm.com> wrote:
> > On 26/07/16 23:30, Dmitry Torokhov wrote:
> 
> >> - I would like to sync up with people and discuss [lack of] progress
> >>   on topic of device probe ordering (including handling of deferred
> >>   probes, asynchronous probes, etc).
> >
> > I'm extremely interested in discussing this.
> 
> I've also tried to pitch in on it in the past but I just feel stupid
> whenever we try to come up with something better than what
> we have :(
> 
> > It has wide reaching consequences as (with my irqchip maintainer hat on)
> > we've had to pretend that some bits of HW (timers, interrupt
> > controllers) are not "devices". Not a massive issue for most, except
> > when your interrupt controller has requirements that are very similar to
> > the DMA mapping API (which you cannot use because "not a device"). Other
> > problems are introduced by things like wire-MSI bridges, and most people
> > end-up resorting to hacks like ad-hoc initcalls and sprinkling deferred
> > probes in specific drivers.
> 
> Same feeling here. I'm accepting patches for random initcall
> reordering because there is nothing else I can do, people need to
> have their systems running. But it feels really fragile.
> 
> Deferred probe alleviated the problem, but I remember saying at
> the time that what we really need to do is build a dependency
> graph and resolve it the same way e.g. systemd does. (Someone
> may have called me BS on that, either for being wrong about everything
> as usual or because of mentioning systemd, I don't know which one.)
> 
> The latest proposal I saw came from Rafael and he had a scratch
> idea for a dependency graph that I really liked, but I guess he's been
> sidetracked since. Rafael, what happened with that?

I got distracted, but Marek Szyprowski has revived it recently.

It needs to be cleaned up somewhat, but other than that I think it's in
a good enough shape to make some progress in that direction, at least in
principle.

Thanks,
Rafael