Re: Help port swsusp to ppc.

[Pavel Machek <pavel@ucw.cz>]

Hi!

> > (1) There's routine during resume that copies pages to their old
> > locations. If you (would want to) have different kernel during resume,
> > how do you guarantee that that "kernel being resumed" does not use
> > memory ocupied by copying routine?
> 
> By having the copy routine sit elsewhere. You can have the copy routine
> be in a known location of the kernel beeing resumed (that is it uses
> its own copy routine) that is aligned on a page boundary and knows how
> to copy itself. Fairly trivial.

I said it is possible to solve. But "copy routine" becomes even more
nasty than it is already.

> > (2) Plus number of problems with devices grows with number of versions
> > squared. To guarantee it works properly you'd have to test all
> > combinations of "suspend kernel" and "resume kernel".
> 
> Why ? You aren't passing any device/driver information from the boot
> kernel and the resumed one... do you ?

I'm not passing device information, but devices *do* have internal
state. I quiesce them before booting new kernel, but there's probably
more than one way to quiesce devices...

> > [(1) Could be solved by reserving 4KB somewhere for copy routine, and
> > making sure copy routine is never bigger than 4KB etc. But I'd like to
> > keep it simple and really don't want to deal with (2).]
> 
> Then you don't wnat to do things properly...

No, I really do not want to make things more complicated in 2.6. And
you should not want to complicate it, too.
								Pavel
-- 
When do you have a heart between your knees?
[Johanka's followup: and *two* hearts?]