[Xen-devel] Re: [linux-pm] [PATCH 0/3] xen: Use PM/Hibernate events for save/restore/chkpt

[Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>]

On Fri, 2011-02-25 at 16:17 +0000, Stefano Stabellini wrote:
> On Mon, 21 Feb 2011, Rafael J. Wysocki wrote:
> > > For a PV guest only the Xen PV drivers really matter.
> > > 
> > > But for a PVHVM guest you are right since there are the emulated "PC"
> > > devices though which could be problematic. There's nothing especially
> > > thrilling in that set of devices although I don't think that invalidates
> > > your point.
> 
> This is a genuine concern because it currently breaks save/restore for
> all PV on HVM guests (dummy_hcd being the offending driver).

Only if !CONFIG_HIBERNATION, right?

> > > > Shouldn't the CONFIG_XEN_SAVE_RESTORE option select CONFIG_HIBERNATION?
> > > > In which case the #ifdef lines in pm_op() wouldn't need to be changed.
> > > 
> > > I think selecting user-visible symbols is generally frowned upon.
> > > 
> > > But apart from that I was concerned that tying the Xen functionality
> > > into the hibernation option was a bit odd/artificial. Perhaps it's the
> > > only solution though.
> > 
> > I'd very much prefer it if the patchset didn't touch 
> > drivers/base/power/main.c.
> > 
> > However, if you want to select CONFIG_HIBERNATION from 
> > CONFIG_XEN_SAVE_RESTORE,
> > you should make sure that CONFIG_HIBERNATION is really selectable (ie.
> > CONFIG_SWAP is set and CONFIG_ARCH_HIBERNATION_POSSIBLE is set).
> 
> I think we should follow this suggestion.

See the thread "[PATCH] xen: fix XEN_SAVE_RESTORE Kconfig dependencies"
from Shriram <1298446066-11754-1-git-send-email-rshriram@xxxxxxxxx>

Ian.


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