[libvirt] [PATCH v1 00/14] Never ending story of user supplied aliases

[Pavel Hrdina]

On Fri, Oct 20, 2017 at 01:20:20PM +0200, Michal Privoznik wrote:
> On 10/19/2017 03:33 PM, Pavel Hrdina wrote:
> > On Thu, Oct 19, 2017 at 10:10:55AM +0200, Michal Privoznik wrote:
> >> As discussed earlier [1], we should allow users to set device
> >> aliases at the define time. While the discussed approach calls
> >> for generating missing aliases too, I'm saving that for another
> >> patch set. There are couple of reasons for that:
> >>
> >> a) I don't think it's really necessary (if users are interested
> >>    in a device they can just set the alias).
> >>
> >> b) This patch set is already big enough as is.
> >>
> >> c) Generating aliases is going to have its own problems.
> >>
> >> Therefore, for now I'm only proposing parsing user supplied
> >> aliases. The idea is that it's not enabled by default for all
> >> drivers. Any driver that want to/can provide this feature has to
> >> set VIR_DOMAIN_DEF_FEATURE_USER_ALIAS. Note that we have some
> >> drivers that don't have notion of device aliases. But the code is
> >> generic enough so that it should be easy to use in the drivers
> >> that do know what aliases are.
> > 
> > This patch series missed some of the important parts of code
> > that relies on our generated aliases:
> > 
> > 1. qemuGetNextChrDevIndex() ... this will fail while attaching new
> >    chardev device without an alias if there is one already provided
> >    by user and doesn't match the one that we generate.
> > 
> > 2. qemuAssignDeviceRedirdevAlias() ... same as 1)
> > 
> > 3. qemuAssignDeviceShmemAlias() ... same as 1)
> 
> Okay, these are easy to resolve.
> 
> > 
> > 4. qemuDomainNetVLAN() ... similar to the previous ones, hot-plugging
> >    network interface with user alias will fail because the alias is used
> >    to figure out VLAN of the interface.
> 
> This one. Well, this function is called only for ancient QEMUs (those
> which lack QMP, and even not for all of them). So do we care? Sure, I
> can cripple my code and allow user aliases only if running sufficiently
> new QEMU. Or just shrug and walk away.

In that case just ignore it, it will print an error message and since
this will affect only hot-plug of network devices with user alias
specified we can claim that this operation is unsupported.

Pavel
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