Re: [Qemu-devel] [PATCH] monitor: Add force option support to pci_del command

[Marcos Oviedo <moviedo.maillist@gmail.com>]

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On Wed, Jun 9, 2010 at 4:38 AM, Gerd Hoffmann <kraxel@redhat.com> wrote:

> On 06/09/10 07:37, Marcos Oviedo wrote:
>
>> This adds a way to force the removal/unplug of previously added pci
>> devices when ACPI-based hotplug mechanism is not present.
>>
>
> Point being?
>
> If your guest can't handle pci hotplug it is pretty useless to plug in
> hardware in the first place.
>
> If your guest supports pci hotplug it will be quite upset if you zap the
> hardware without asking via ACPI.
>

This make sense when you mistakenly add a pci device on a -s -S scenario,
like the scenario described on the following bug:
https://bugs.launchpad.net/qemu/+bug/544367.

When ACPI-based hotplug support is present on the guest and we run pci_del
with the force option, the hotplug events will still be generated to the
guest and the guest still will trigger the EJx event, which will end by
calling pciej_write() on qemu side. This function will do nothing on a -f
and pci hotplug support scenario, as the pci device was previously removed
by pci_del.

Thanks!

Marcos



>
> cheers,
>  Gerd
>
>

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