Re: [linux-pm] [suspend/resume] Re: userspace notification from module

From: Rafael J. Wysocki
Date: Tue Jan 05 2010 - 16:23:15 EST


On Tuesday 05 January 2010, BartÅomiej ZimoÅ wrote:
> Dnia 5 stycznia 2010 10:07 Anders Eriksson <aeriksson@xxxxxxxxxxx> napisaÅ(a):
> >
> > rjw@xxxxxxx said:
> > >> > I don't see a problem with this in principle, although I don't think signals
> > >> > are very suitable for this particular purpose, because you need two-way
> > >> > communication between the power manager and the processes it's going to
> > >> > notify (because it has to wait for the processes to finish their preparations
> > >> > and to tell it that they are ready).
> >
> > Wouldn't there need to be dependecy tracking for the userspace processes? A
> > process couldn't signal "done" until it know there's no more work to do, which
> > requires all other processes to finish up first.
> >
>
> Not all processes will need pm notification.
>
> Just in case, could this "power manager" be provided as userspace
> driver for kernel (for example compiled as UIO)?

I don't really understand why you want to do that in the kernel. Is there
any particular reason why this cannot be done in the user space?

Rafael
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