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@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. -- Eduardo
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@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
participants (1)
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Eduardo Habkost