Re: [Qemu-devel] [PATCH v2 4/7] bootindex: delete bootindex when device is removed

[Eduardo Habkost]

On Wed, Jul 30, 2014 at 07:29:56AM +0000, Gonglei (Arei) wrote:
> Hi,
> 
> > -----Original Message-----
> > From: Gerd Hoffmann [mailto:address@hidden
> > Sent: Friday, July 25, 2014 5:52 PM
> > 
> > > +    del_boot_device_path(dev);
> > 
> > You can call this from device_finalize() instead of placing it into each
> > individual device.
> > 
> Maybe put this call in device_finalize is not a good idea. 
> I have three reasons:
> 
> 1. the device's some memory have been freed before call device_finalize,
>  such as device->id. It is too later.

I don't think you even need id. See my reply to v4 2/8.

But you have a point about being too late: some devices call
add_boot_device_path() on realize, so those would need to revert the
operation on unrealize; others do it on init, so they need to do it on
finalize.

On either case, I believe an extra check inside device_finalize()
wouldn't hurt, even if it becomes redundant on some devices.


> 2. not every kinds of device can configure bootindex property, such as usb
>  host adapters. It is a waste and useless for those devices. This is the
>  main reason.

I would prefer to waste a few cycles scanning the boot index list every
time a device is removed, than risking crashing QEMU in case somebody
forget to add a del_boot_device_path() call.


> 3. virtio-net device's parent is virtio-pci device, which configured id 
> property,
>  But the device saved in global fw_boot_order list is virtio-net device have 
> not
>  id property. If we put call del_boot_device_path(dev) in 
> virtio_net_device_unrealize
>  we can delete it from fw_boot_order directly.

Sorry, I don't understand what you mean here. If virtio-net doesn't have
an id property, would the current version of del_boot_device_path() even
work?

-- 
Eduardo