Re: [Xen-devel] [Qemu-devel] [PATCH 1/4] Introduce a new hotplug state: Force eject.

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Wed, May 16, 2012 at 11:32 AM, Stefano Stabellini
<stefano.stabellini@xxxxxxxxxxxxx> wrote:
> On Tue, 15 May 2012, Michael S. Tsirkin wrote:
>> On Tue, May 15, 2012 at 04:26:36PM +0100, Anthony PERARD wrote:
>> > This hotplug state will be used to remove a device without the guest
>> > cooperation.
>> >
>> > Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
>>
>> This can crash guest, can't it? If you are fine with crashing guest,
>> we already let you do this:
>> - delete device
>> - reset guest
>> no need for new flags.
>
> Given that the guest is not going to crash (if it knows what it is
> doing), we could just:
>
>
> diff --git a/hw/xen_platform.c b/hw/xen_platform.c
> index a9c52a6..a1e1a33 100644
> --- a/hw/xen_platform.c
> +++ b/hw/xen_platform.c
> @@ -88,6 +88,7 @@ static void unplug_nic(PCIBus *b, PCIDevice *d)
> Â Â if (pci_get_word(d->config + PCI_CLASS_DEVICE) ==
> Â Â Â Â Â Â PCI_CLASS_NETWORK_ETHERNET) {
> Â Â Â Â qdev_unplug(&(d->qdev), NULL);
> + Â Â Â Âqdev_free(&(d->qdev));
> Â Â }
> Â}
>
>
> Anthony, can you confirm that this solves the problem for you?

This work until I try to hotplug a new device to the guest at wish
point I have this:
ERROR:/local/home/anthony/work/qemu/qom/object.c:389:object_delete:
assertion failed: (obj->ref == 0)

This is because there is still a pending request of the hotunplug in
the acpi piix4.
If I call qdev_free without qdev_unplug, I hit the same assert, but
rigth away. This is way something new.

-- 
Anthony PERARD

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