Re: Changes to PM layer break userspace

From: David Brownell
Date: Sun Dec 24 2006 - 02:02:44 EST

On Friday 22 December 2006 1:09 pm, Pavel Machek wrote:
> 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 ...
> > >
> > > 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.

So exactly what tool on Ubuntu uses this? Without any "dangerous!
aggressive! experimental!" read-lights-siren-alarms-ringing alert level?

Seems to me anyone really desperate to put PCI devices into a low
power mode, without driver support at the "ifdown" level, would be
able just "rmmod driver; setpci". Without risking software bugs.
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