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(a)redhat.com +1-801-349-2682
Libvirt virtualization library http://libvirt.org
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