Re: [libvirt] [PATCH alt] conf: Allow user define their own alias
On Fri, Sep 29, 2017 at 09:06:01AM +0200, Michal Privoznik wrote:
https://bugzilla.redhat.com/show_bug.cgi?id=1434451
It comes handy for management application to be able to have a
per-device label so that it can uniquely identify devices it
cares about. The advantage of this approach is that we don't have
to generate aliases at define time (non trivial amount of work
and problems). The only thing we do is parse the user supplied
tag and format it back. For instance:
<disk type='block' device='disk'>
<driver name='qemu' type='raw'/>
<source dev='/dev/HostVG/QEMUGuest1'/>
<target dev='hda' bus='ide'/>
<alias user='myDisk0'/>
<address type='drive' controller='0' bus='0'
target='0' unit='0'/>
</disk>
Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
---
An alternative approach to:
https://www.redhat.com/archives/libvir-list/2017-September/msg00765.html
Honestly, I prefer this one as it's simpler and we don't have to care about
devices changing their aliases on cold plug. I mean, on cold (un-)plug we'd
have to regenerate the aliases so it might be hard to track certain device.
But with this approach, it's no problem.
Can you elaborate on you mean by the cold plug problem here ?
Are you saying that if you cold plug a single device, we would regenerate
aliases on every single other device too ? I would surely think we can
avoid that kind of thing.
To make hotplug easier for applications we could add a V2 hotplug API
which *returns* the fully-expanded device XML.
That way applications would immediately learn the alias of the newly
hotplugged device in a simple manner.
While we were at it, this would give us opportunity to make the v2
hotplug API support hotplugging of multiple devices at once. This is
a feature we've needed for PCI assignment where some devices have to
be co-assigned at the same time.
Regards,
Daniel
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