Date: Tue, 16 Jul 2013 12:22:45 +0200
From: Igor Mammedov <imammedo@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v5 05/14] vl: handle "-device dimm"
To: Hu Tao <hutao@cn.fujitsu.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>, qemu-devel@nongnu.org, Vasilis Liaskovitis <vasilis.liaskovitis@profitbricks.com>, Bandan Das <bsd@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, gaowanlong@cn.fujitsu.com

On Tue, 16 Jul 2013 15:27:19 +0800
Hu Tao <hutao@cn.fujitsu.com> wrote:

> On Tue, Jul 16, 2013 at 08:19:48AM +0200, Paolo Bonzini wrote:
> > Il 16/07/2013 03:27, Hu Tao ha scritto:
> > > > I think it's the same.  One "-numa mem" option = one "-device dimm"
> > > > option; both define one range.  Unused memory ranges may remain if you
> > > > stumble upon a unusable range such as the PCI window.  For example two
> > > > "-numa mem,size=2G" options would allocate memory from 0 to 2G and from
> > > > 4 to 6G.
> > > 
> > > So we can drop -dimm if we agree on -numa mem?
> > 
> > Yes, the point of the "-numa mem" proposal was to avoid the concept of a
> > "partially initialized device" that you had for DIMMs.
> > 
> > BTW, how do you specify which module you are plugging in?  I.e., what if
> > I have three 1G ranges at 0, 1G and 2G, and I want to plug the first and
> > the third?
> 
> I think an id is still needed to identify ranges, which can be shown to
> user with `info numa' or similar command, along with the corresponding
> ranges.
"info numa" could get actual ranges enumerating present dimms if we would use
plain -device for hotplug memory instead of -numa mem hacking.

> 
> > 
> > This is especially important with hot-unplug, because then you can have
> > this kind of hole in the address space.  If you migrate the VM, you have
> > to reproduce the situation in the destination command line.
> > 
> > Paolo
> > 
>