Re: [Xen-devel] [PATCH v9 1/9] xen: vnuma topology and subop hypercalls

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 03.09.14 at 02:46, <ufimtseva@xxxxxxxxx> wrote:
> On Fri, Aug 29, 2014 at 6:37 AM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>>>>> On 29.08.14 at 05:04, <ufimtseva@xxxxxxxxx> wrote:
>>> +static struct vnuma_info *vnuma_init(const struct xen_domctl_vnuma *uinfo,
>>> +                                     const struct domain *d)
>>> +{
>>> +    unsigned int nr_vnodes;
>>> +    int i, ret = -EINVAL;
>>> +    struct vnuma_info *info;
>>> +
>>> +    nr_vnodes = uinfo->nr_vnodes;
>>> +
>>> +    if ( nr_vnodes == 0 || nr_vnodes > uinfo->nr_vmemranges ||
>>
>> Is that really a necessary check? I.e. does code elsewhere rely on
>> that? I ask because memory-less nodes are possible on real
>> hardware.
> 
> That is true. But taking into account that there are no buses support
> yet added, absence of memory and buses for a vNUMA node
> seem to be useless. And vNUMA can mimic hardware NUMA as close as
> possible, but I think the degree of this is pretty much our choice.
> With further extension of vNUMA to include buses I think this check
> will naturally disappear.

I have to admit that I struggle with the references to "buses" in your
reply. Could you perhaps give some context (not the least because
already known future extensions may call for making provisions for
them in the public interface)?

Jan


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