Re: Changes to PM layer break userspace

From: Pavel Machek
Date: Sat Dec 23 2006 - 04:38:42 EST


Hi!

> > The existence of the power/state interface wasn't a bug - it was a
> > deliberate decision to add it. It's the only reason the
> > dpm_runtime_suspend() interface exists.

Actually, if we noticed power/state during PM framework review, it
would have been killed. It is just way too ugly.

> > > In contrast, the /sys/devices/.../power/state API has never had many
> > > users beyond developers trying to test their drivers (without taking
> > > the whole system into a low power state, which probably didn't work
> > > in any case), and has *always* been problematic. And the change you
> > > object to doesn't "break" anything fundamental, either. Everything
> > > still works.
> >
> > It's used on every Ubuntu and Suse system,
>
> Odd how the relevant Suse developers didn't mention any issues with
> those files going away, any of the times problems with them were
> discussed on the PM list. Also, I have a Suse system that doesn't
> use those files for anything ... maybe only newer release use it.

Not on *every* suse system. power/state is known to oops kernels, so
it is only enabled when user explicitely asks for 'dangerous aggresive
experimental power saving' or something like that.
--
Thanks for all the (sleeping) penguins.
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