Re: [Qemu-devel] [PATCH v2] pc: allow raising low memory via max-ram-below-4g option

[Michael S. Tsirkin]

On Fri, Jan 22, 2016 at 11:51:54AM +0100, Gerd Hoffmann wrote:
>   Hi,
> 
> > > > I wonder whether we should just bite the bullet and ask management to
> > > > maintain the physical memory map for us, instead of trying to give us
> > > > hints.
> > > 
> > > I doubt this simplified things, given the backward compatibility
> > > constrains we have.
> > > 
> > > cheers,
> > >   Gerd
> > 
> > That's exactly what would become simple.
> > For backwards compatibility we would leave things alone
> > if the new flags for the memory map aren't specified.
> 
> But we'll add a bunch of new code for the new config mode which allows
> management to maintain the physical memory map.  And we'll expect
> management know about a bunch of machine type internals.


Yes we don't want that. I was vaguely thinking some kind
of query that reports the required info so management
just has to maintain that.


>  That isn't a
> simplification.
> 
> > This would allow people to e.g. allocate phy address
> > ranges for things like nvdimm which has been
> > problematic in the past.
> 
> Didn't follow nvdimm discussions.  If you think we really need that
> anyway to solve certain issues, sure, go ahead and I happily adjust this
> patch to use the new infrastructure.
> 
> cheers,
>   Gerd


I'd like to gather some feedback from management folk first.

-- 
MST