hibernation support - lack of distro-wide coordination between systemd, dracut, anaconda, pm-utils and maybe more?

[Bastien Nocera]

----- Original Message -----
> On Wed, Apr 15, 2015 at 10:26:14AM -0400, Bastien Nocera wrote:
> > 
> > 
> > ----- Original Message -----
> > > On Tue, Apr 14, 2015 at 09:30:31AM -0600, Chris Murphy wrote:
> > > > On Tue, Apr 14, 2015 at 3:07 AM, Bastien Nocera <bnocera at redhat.com>
> > > > wrote:
> > > > >
> > > > >
> > > > > ----- Original Message -----
> > > > >> OK not everyone is on the same page, apparently. This bug was just
> > > > >> closed by Anaconda as WONTFIX.
> > > > >>
> > > > >> suggested swap for laptop seems low
> > > > >> https://bugzilla.redhat.com/show_bug.cgi?id=1037472
> > > > >>
> > > > >> I don't see how hibernation works reliably with such a low default
> > > > >> swap
> > > > >> size.
> > > > >
> > > > > This isn't the way to fix it. The hibernation file/partition should
> > > > > really be independent
> > > > > of swap, because 1) you can't be sure how much swap will actually be
> > > > > used
> > > > > by the applications
> > > > > so you can't be sure you'll ever have enough swap to save the RAM 2)
> > > > > Too
> > > > > much swap and the
> > > > > (lack of) interactivity will make you want to advocate physical
> > > > > violence
> > > > > when your machine
> > > > > is unusable for an hour because of a hungry Javascript in your 50th
> > > > > Firefox tab.
> > > > 
> > > > Windows and OS X both use swapfiles rather than swap partition, and a
> > > > sleep image file rather than a partition. OS X's swapfiles are
> > > > dynamically created on demand in variable size increments.
> > > I think the problem is in the ways filesystems are implemented.  The
> > > fs has to be mounted to access the swap file, and this can change the
> > > fs, even with a read-only mount. Because we don't have
> > > really-read-only fs mounting, we need to support swap-as-partition, so
> > > we might just as well use it by default.
> > > 
> > > > Both OS's have a feature that I find invaluable on a laptop which is
> > > > the automatic switch from suspend-to-RAM to suspend-to-disk.
> > > Yes, integrating with firmware would be great. So far this hasn't been
> > > hapenning...
> > > What we can do instead is use hybrid sleep. It's not smart at all,
> > > and doesn't prevent your battery from draining completely, but it does
> > > protect
> > > your data.
> > > 
> > > Systemd supports hybrid-sleep as another option analogous to suspend
> > > and hibernation, so for anything using systemd to suspend swithing to
> > > hybrid should be trivial. Maybe we should make this an F23 goal:
> > > - use hybrid-sleep from Gnome and other DE by default
> > 
> > Hybrid sleep as offered in systemd still is just suspend + hibernation, and
> > the way we do hibernation is broken.
> Can you be more specific? Do you consider hibernate-to-swap-partition
> unacceptable?

I think that conflating "memory-to-disk swap space" with "I can hibernate my machine"
is unacceptable. We need a new partition type that Anaconda would setup, or
a whitelist of laptops with firmwares that support rapid start (and again, Anaconda
to set it up), or use a temporary file of any sort to store the hibernation data.

If my machine has 8 gigs of memory, I don't want to need 8 gigs plus of swap to be
able to hibernate it, when run away processes can make my machine unusable for hours
if they start hitting that swap.

> > Hybrid sleep is already the default on low battery with newer versions of
> > UPower.
> Yeah, I wasn't aware of that. This should be a good thing.
> 
> Zbyszek
>  
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