[libvirt] [PATCH 08/12] vcpu: support maxvcpu in domain_conf

[Eric Blake]

On 10/01/2010 09:01 AM, Daniel Veillard wrote:
> On Wed, Sep 29, 2010 at 06:02:12PM -0600, Eric Blake wrote:
>> * src/conf/domain_conf.h (_virDomainDef): Adjust vcpus to unsigned
>> short, to match virDomainGetInfo limit.  Add maxvcpus member.
> [...]
>>
>> Two tightly-related changes.  One: virDomainGetInfo implicitly limits
>> vcpus to a 16-bit number; so there's no need to pretend otherwise
>> through the rest of the code.
>
>   well, yes and no, in a few years we may look ridiculous, but it would
>   be good to have the new APIs cleared up from that limitation.

So, should I keep the change to 16-bit in my v2 series, or should I keep 
things at 32-bit and add code that makes virDomainGetInfo fail on 16-bit 
overflow?  Right now, it's easier to keep things at 16-bit throughout. 
Also, note that the new APIs (virDomainGetVcpusFlags and 
virDomainSetVcpusFlags) can go up to 31 bits.  Get must return -1 on 
failure, so a full 32-bits cannot be returned; so even though Set passes 
an unsigned value, we should not accept 0x80000000, even if we decide 
someday that we want to support 0x10000 vcpus.

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org