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

[Anthony Liguori <aliguori@us.ibm.com>]

Eric Blake <eblake@redhat.com> writes:

> 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 <bsd@redhat.com>
>>>
>>> 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

That's fine for libvirt, but we don't break command line compatibility
in QEMU.  So this patch needs to change.

Regards,

Anthony Liguori

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