Re: [Qemu-devel] [PATCH V4 01/10] NUMA: Support multiple CPU ranges on -numa option

[Eric Blake]

On 07/05/2013 12:41 PM, Eduardo Habkost wrote:
> On Thu, Jul 04, 2013 at 05:53:08PM +0800, Wanlong Gao wrote:
>> From: Bandan Das <address@hidden>
>>
>> This allows us to use the "cpus" property multiple times
>> to specify multiple cpu (ranges) to the -numa option :
>>
>> -numa node,cpus=1,cpus=2,cpus=4
>> or
>> -numa node,cpus=1-3,cpus=5
>>
>> Note that after this patch, the defalut suffix of "-numa node,mem=N"
>> will no longer be "M". So we must add the suffix "M" like "-numa node,mem=NM"
>> when assigning "N MB" of node memory size.
> 
> Such an incompatible change is not acceptable, as it would break
> existing configurations. libvirt doesn't specify any suffix and expects
> it to always mean "MB".

Newer libvirt can be taught to append 'M' when it detects it is talking
to newer qemu.  While you have a point that it is annoying to force
users to upgrade to a newer libvirt merely because they upgraded qemu,
the libvirt point of view is that the following are supported:

old libvirt -> old qemu
new libvirt -> old qemu
new libvirt -> new qemu

but that this combination is always best effort and not required to work:

old libvirt -> new qemu

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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