Re: [Xen-devel] [PATCH] Disallow setting maxmem to higher value than total physical memory size

[Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>]

On Wed, 2010-09-01 at 22:10 +0100, Jeremy Fitzhardinge wrote:
> 
> > It's not only in xenstore, it is also in the result of the
> > XENMEM_get_memory_map hypercall.
> 
> Is that separate from 3?

As far as the h/v is concerned yes. Although they know it's an e820 the
set/get_memory_map hypercalls basically store an opaque blob so far as
the h/v is concerned. xend doesn't seem so sure they are unrelated...

> > Old-style PV Linux domains really do use static-max in this way. It may
> > well be that there are potentially better ways for guests to implement
> > this in the future but we have a deployed base of guests which work this
> > way.
> 
> I specifically meant the Xenstore "static-max" value is useless. 
> Getting it via hypercall is fine.

I'm not sure but I think this is used by HVM balloon drivers when PoD is
active. I don't know why this is the case though, other than
XENMEM_get_memory_map being a PV only hypercall.

Ian.


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