Re: [PATCH 2/2] Fix console handling during suspend/resume

Linus Torvalds
2006-06-15T19:40:39Z

On Thu, 15 Jun 2006, Pavel Machek wrote:
>
> Well, it is right that separation as you suggest is possible... but it
> is quite different from current system. And if someone does suspend
> (instead of freeze) -- no harm is done -- it just takes
> longer.

Sure, harm IS done.

Suspending a device before everybody else has saved their state is
fundamentally and deeply wrong. You do not know whether other devices
might need that device for their state save.

You may, for example, have devices that literally have so much state that
they need user help to save it - which in turn means that they must be
saved before you have suspended other and UNRELATED devices. X itself is
actually an example of this, but so might be anything with firmware, for
example).

(Right now, we actually end up saving firmware in kernel memory or do
things like that, so that we can resume it. That's really a hack for the
bigger problem of not having multiple stages of save/restore.)

It's not just firmware. It could be things like devices that literally
have user processes handling connection setup etc for them.

So the whole notion of mixing "save state" and "suspend" is fundamentally
wrong. It has _always_ been wrong. And it's very fundamentally wrong in a
way that makes me say that unless you can separate the two (not just in
a technical sense, but in the sense of how people literally _think_ about
the suspend problem), we can probably _never_ fix the deeper issues.

Linus