Re: Thoughts wanted on merging Software Suspend enhancements

Pavel Machek
2003-07-12T15:22:50Z

Hi!

> Don't ask me why I'm awake at 3am. I don't know.

;-). Its 5pm here...

> > Well, you probably did want Linus to answer, but I see some new stuff
> > here.
>
> Yeah, I did. But it wasn't going to happen :>

Well, Linus just tends to drop the mail. [Killed him from Cc].

> > > - save a full image rather than freeing just about all the memory first
> > > - highmem support
> > > - image compression support
> > > - swapfile support in progress
> >
> > This seems extremely hard to do right. If you can do it right and not
> > rewrite half of kernel, that's okay, but I don't think you can do that.
>
> I assume you mean swapfile only. The first two have been working for a
> while now. For swapfile support, my approach is simple. I'll store the
> info rw_swap_page_base calculates and save it in the pagedir, using it
> to read back the data at resume without requiring any knowledge of the
> filesystem. (Of course I'm assuming the data isn't compressed etc but
> since swapfiles work, this seems to be a reasonable assumption; I can
> always mirror changes in the swapfile code). I'll also take advantage of
> the fact that much of the pagedir data we're storing is very easily
> compressable itself to ensure that this doesn't result in severe bloat
> of the pagedirs. I've already got a little patch to test it the theory,
> and results look very encouraging but I won't try to explain it here.
> I'll just confuse the issue.

Okay, that's sane approach to do it... But where do you store pointer
to pagedir?

> > > - nice display
> > > - user can abort at any time during suspend (oh, I forgot, I wanted
> > > to...) by just pressing Escape
> >
> > That seems like missfeature. We don't want joe random user that is at
> > the console to prevent suspend by just pressing Escape. Maybe magic
> > key to do that would be acceptable...
>
> Magic key? Do you mean a password? I suppose that could be a

Documentation/sysrq.txt. Magic sysrq driver will answer some
interesting questions like "how to press esc on the serial line", etc,
and it is also /proc configurable.

Pavel
--
When do you have a heart between your knees?
[Johanka's followup: and *two* hearts?]