Re: [Xen-devel] [PATCH v3 4/8] x86/vm_event/monitor/cr: check for vm-event subscriber on domctl

[Corneliu ZUZU <czuzu@xxxxxxxxxxxxxxx>]

On 7/6/2016 7:15 PM, Corneliu ZUZU wrote:
> On 7/6/2016 7:01 PM, Jan Beulich wrote:
> > > > > On 06.07.16 at 17:52, <czuzu@xxxxxxxxxxxxxxx> wrote:
> > > Also adjust returned error code for similar check from -EINVAL to more
> > > descriptive -ENOSYS (XEN_DOMCTL_MONITOR_OP_EMULATE_EACH_REP).
> > I'm not sure that's more descriptive, and we really try to not use
> > ENOSYS for other than unimplemented hypercalls. EOPNOTSUPP
> > perhaps?
> >
> > Jan
> Well,  it's not quite an 'unsupported operation' and neither does the 
> toolstack user communicate an 'invalid value', he must just be noticed 
> that something (the vm-event subsystem) needs to be initialised before 
> the operation can be done.
> But I agree ENOSYS is not acceptable either (I only now see it 
> signifies "Function not implemented", my bad for not peeking at that 
> before using it, I expected differently).
> What about ENODEV, i.e. "No such device."? We need an error code 
> saying "Device not initialised"...
> Thanks,
> Corneliu.
Or ENOTCONN..?

Corneliu.

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