[libvirt] [Qemu-devel] [PATCH] qdev: Make "hotplugged" property read-only

[Eduardo Habkost]

On Tue, Jan 03, 2017 at 03:06:02PM -0200, Eduardo Habkost wrote:
> (CCing libvir-list and Laine)
> 
> On Tue, Jan 03, 2017 at 05:53:27PM +0100, Igor Mammedov wrote:
> > On Tue, 3 Jan 2017 17:10:15 +0100
> > Paolo Bonzini <pbonzini at redhat.com> wrote:
> > 
> > > 
> > > 
> > > On 03/01/2017 15:22, Eduardo Habkost wrote:
> > > >> I didn't know that. Is this documented somewhere?
> > > >> Is it actually used by any existing software?
> > > > not that I know of. But users should be fixed if they are not using it.
> > > > 
> > > > I see. The problem is that the mechanism is undocumented,
> > > > untested, and seems very likely to trigger bugs in device code.
> > > 
> > > I agree.  Why can't hotplugged be migrated?
> > It's probably not migrated because of it's not runtime/guest modified
> > state so we don't have to migrate it as it's know in advance.
> > 
> > For now it should set manually on CLI (-device) with the rest of
> > hotplugged device properties.
> 
> As this recommendation has the potential to trigger hidden bugs
> (and known to trigger a bug in QEMU <= 2.8), I would like it to
> be properly documented, and the documentation/recommendations
> reviewed following the usual patch review process.
> 
> While we don't do that, setting "hotplugged=true" on the
> command-line is an unused, undocumented, untested (and
> unsupported?) feature.

As the ability to set hotplugged=true is still unused and
undocumented, I will resubmit this patch to disable the feature
in QEMU 2.9.

-- 
Eduardo