Re: [linux-pm] [RFC] userland swsusp

[Greg KH]

On Wed, Nov 16, 2005 at 05:00:45PM +1100, Nigel Cunningham wrote:
> Hi.
> 
> On Wed, 2005-11-16 at 17:14, Greg KH wrote:
> > On Wed, Nov 16, 2005 at 06:35:30AM +0200, Dumitru Ciobarcianu wrote:
> > > ??n data de Mi, 16-11-2005 la 00:32 +0100, Pavel Machek a scris:
> > > > ...but how do you provide nice, graphical progress bar for swsusp
> > > > without this? People want that, and "esc to abort", compression,
> > > > encryption. Too much to be done in kernel space, IMNSHO.
> > > 
> > > Pavel, you really should _listen_ when someone else is talking about the
> > > same things in different implementations. suspend2 has this feature
> > > (nice graphical progress bars in userspace) for a long time now and it's
> > > compatible with the fedora kernels.
> > 
> > It's also implemented in the kernel, which is exactly the wrong place
> > for this.  Pavel is doing this properly, why do you doubt him?
> 
> You yourself called it a hack not long ago.

I did, in the proud tradition of neat hacks.  It's a very nice
accomplishment that this even works, and I'm impressed.

> I'm not sure why you think the userspace is the right place for
> suspending.

If he can come up with an implementation that works, and puts stuff like
the pretty spinning wheels and progress bars and encryption in
userspace, that's great.  That stuff doesn't belong in the kerenel if we
can possibly help it.

> It seems to me that the very fact that it requires access to
> structures that are normally only visible to the kernel is pretty
> telling.

So it needs some work :)

> To be fair, it is true at the same time that graphical interfaces
> don't belong in the kernel - but the vast majority of it - calculating
> what to write and doing the writing does. It's only by hamstringing
> himself and the user - limiting the image to half of memory that Pavel
> (and dropping support for writing to swap) that Pavel can make this
> work.

Then propose a better way to do this, if you can see one.

> > > Why don't you and Nigel (of suspend2) can just work together on this ?
> > > It's a shame that much work is wasted in duplicated effort.
> > 
> > It's not duplicated, Nigel knows what need to be done to work together,
> > if he so desires.
> 
> I know that Pavel and I have such different ideas about what should be
> done that it's not worth the effort.

I'm sorry that you feel this way.  I thought that after our meeting in
July that things were different.

thanks,

greg k-h
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