On Mon, Apr 23, 2012 at 04:31:04PM +0300, Avi Kivity wrote:
On 04/22/2012 05:20 PM, Gleb Natapov wrote:
On Sun, Apr 22, 2012 at 05:13:27PM +0300, Avi Kivity wrote:
On 04/22/2012 05:09 PM, Gleb Natapov wrote:
On Sun, Apr 22, 2012 at 05:06:43PM +0300, Avi Kivity wrote:
On 04/22/2012 04:56 PM, Gleb Natapov wrote:
start. We will need it for migration anyway.
> hotplug-able memory slots i.e. initial system memory is not modeled with > memslots. The concept could be generalized to include all memory though, or it > could more closely follow kvm-memory slots. OK, I hope final version will allow for memory < 4G to be hot-pluggable.
Why is that important?
Because my feeling is that people that want to use this kind of feature what to start using it with VMs smaller than 4G. Of course not all memory have to be hot unpluggable. Making first 1M or event first 128M not unpluggable make perfect sense.
Can't you achieve this with -m 1G, -device dimm,size=1G,populated=true -device dimm,size=1G,populated=false?
From this:
(for hw/pc.c PCI hole is currently [below_4g_mem_size, 4G), so hotplugged memory should start from max(4G, above_4g_mem_size).
I understand that hotpluggable memory can start from above 4G only. With the config above we will have memory hole from 1G to PCI memory hole. May be not a big problem, but I do not see technical reason for the constrain.
(I don't think hotplugging below 512MB is needed, but I don't have any real data on this).
512MB looks like a reasonable limitation too, but again if there is not technical reason for having the limitation why have it?
I was thinking about not having tons of 128MB slots, so we don't have a configuration that is far from reality. But maybe this thinking is too conservative.
I think it is good interface to make memory that is specified with -m to be one big unpluggable slot, but slots defined with -device should start just above what -m specifies (after proper alignment). Memory hot-plug granularity is controlled by slot's size parameter.
-- Gleb.