Re: [Xen-devel] [PATCH v3 1/3] libxl: xl mem-max et consortes must update static-max in xenstore too

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

Daniel Kiper writes ("Re: [Xen-devel] [PATCH v3 1/3] libxl: xl mem-max et 
consortes must update static-max in xenstore too"):
> On Tue, Apr 09, 2013 at 02:10:53PM +0100, Ian Jackson wrote:
> > The reason for xl using static-max is that in the absence of memory
> > hotplug, attempting to raise a guest above static-max will not work.
> > And this check takes effect in xl.
> 
> OK but now it is quiet difficult (or close to impossible) to know
> in advance that a given guest supports memory hotplug or not.

Right.

> That is why I think that static-max should be unconditionally
> changed or the guest should write something in xenstore to inform
> that it supports memory hotplug and relevant check should be waived.

Right.  I don't see what any of that has to do with "xl mem-max"
though.  The purpose of xl mem-max is to update the guest's
enforcement limit.

I think it would be great for the guest to write something to xenstore
saying it supports memory hotplug.  How does the protocol work ?  The
guest writes "I support memory hotplug", and the tools then ignore
static-max and simply update the memory target with a new value ?  Do
the tools need to do anything else ?

Ian.

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