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Re: [Qemu-devel] [PATCH] qdev: DEVICE_DELETED event
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-devel] [PATCH] qdev: DEVICE_DELETED event |
Date: |
Thu, 07 Mar 2013 10:38:33 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.1 (gnu/linux) |
Eric Blake <address@hidden> writes:
> [adding libvirt]
>
> On 03/06/2013 07:52 AM, Paolo Bonzini wrote:
>> Il 06/03/2013 15:44, Eric Blake ha scritto:
>>> Question - if libvirt misses the event (for example, if libvirtd
>>> requests a remove, but then gets restarted, and the event arrives before
>>> libvirtd is back up), is there a way to poll whether the the removal has
>>> completed? The event is great to minimize polling overhead in the
>>> common case, but we generally provide this sort of information via a
>>> pollable interface at the same time.
General rule: no event without a way to poll.
>> Yes, you can use qom-list on /machine/peripheral.
>
> Which means libvirt should be patched to use qom-list right now, even
> before this event makes it in, in order to avoid its current bug of
> reusing a device id before the deletion has completed. Adding the event
> is still useful, as polling is never nice; and we already know how to
> make libvirt do conditional code based on whether query-events shows
> that the event has been added to minimize polling where possible.
Yes.