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RE: [Xen-devel] [Question] How to support page offline in Xen environment

Tim, do you think this code path will keep guest's service continue (that's one 
reason we considered LM method before). Seems from the code, the guest will be 
down for very short time, but I'm not qutie sure. I'm still trying to reading 
the code.

Yunhong Jiang

xen-devel-bounces@xxxxxxxxxxxxxxxxxxx <> wrote:
>> Have a look at the code for xc_domain_resume in libxc/xc_resume.c.  The
>> slow-and-safe version makes the domain state look like it would after a
>> save/restore, so that older kernels can be resumed after they've paused
>> and had their state saved.  The fast version just changes the return
>> code that the guest will see from its shutdown hypercall.
>> My suggestion is that you cause the guest to stop like it would for a
>> save to disk, shuffle its p2m around, and call the slow-path resume
>> function so that it will pick up the new p2m properly.
> I will dig-into the code  Thanks for your suggestion.
>>> Do you mean the "something very lightweight based on small parts of
>>> the save/restore code" is done in management tools, not in HV, am I
>>> right?
>> Yes.  For the common case this lets you get what you want without the
>> hypervisor being involved.
> So maybe the policy can be: if HV can offline page easily
> (like page owned by hvm domain without device assigned, or
> free pages), HV will do that, otherwise, we will leave it to user space
> tools. 
> We will firstly implement the code in HV side.
>> Cheers,
>> Tim.
>> --
>> Tim Deegan <Tim.Deegan@xxxxxxxxxx>
>> Principal Software Engineer, Citrix Systems (R&D) Ltd.
>> [Company #02300071, SL9 0DZ, UK.]
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