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Re: [libvirt] [PATCHv4 1/4] vcpupin: inroduce a new libvir API (virDomainPinVcpuFlags)

On 05/20/2011 02:54 PM, Adam Litke wrote:
> I am really confused about what the default flags
> (VIR_DOMAIN_VCPU_CURRENT) actually means.  It doesn't seem like I can
> ever know what it means from an API perspective (since it's behavior is
> arbitrary depending on the hypervisor).  Wouldn't it be better to
> require _either_ VIR_DOMAIN_VCPU_LIVE _or_ VIR_DOMAIN_VCPU_CONFIG to be
> set so that the intended behavior can be set with specificity?

Anywhere we use _CURRENT, it is supposed to mean _LIVE (if the VM is
running) or _CONFIG (if the VM is persistent but offline).

Yes, explicitly specifying _LIVE, _CONFIG, or the combination of both,
is probably better.

And in the past, we haven't always used those conventions; that is,
there are some APIs where _CURRENT is non-zero, and the default (0) was
unclear in its meaning.  But all new APIs should use _CURRENT as 0, so
that the default has clear semantics.

However, there are some hypervisors that cannot do just _LIVE on
persistent domains - they can only do _LIVE|_CONFIG (for transient
domains, though, it should be obvious that just _LIVE works, since
_CONFIG cannot succeed on a transient domain).

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

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