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

(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(a)redhat.com&gt; 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.