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

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Fri, 25 Feb 2011, Ian Campbell wrote:
> 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?

Yes

> > > > > 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>

Thanks, I am a bit behind schedule with my unread emails...

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