On 5 April 2013 17:47, Anthony Liguori <[email protected]> wrote:
> Kevin Wolf <[email protected]> writes:
>
>> From: KONRAD Frederic <[email protected]>
>>
>> The virtio-blk-x configuration is not in sync with virtio-blk configuration.
>> So this patch remove the virtio-blk-x configuration field, and use virtio-blk
>> one for setting the properties.
>>
>> This also remove a useless configuration copy in virtio_blk_device_init.
>>
>> Signed-off-by: KONRAD Frederic <[email protected]>
>> Tested-by: Cornelia Huck <[email protected]>
>> Signed-off-by: Kevin Wolf <[email protected]>
>
> This breaks -M pc-1.0 as it breaks global properties.
The first level analysis of why this happens:
(1) global values are set as part of DeviceState's instance_init function
[and we set the config_wce field to 0 here]
(2) virtio_blk_pci_instance_init is a subclass instance_init so runs second
(3) it calls object_initialize on its embedded virtio-blk object
(4) the DeviceState instance_init for that child object sets the
properties to their init values [thus resetting config_wce to 1]
The effect is that at the moment you can't have a property on
a parent object whose value is stored in the child object
(unless you do something hacky like read the default before
calling object_initialize and restore it afterwards].
It seems to me that the underlying problem here is that we
set global values too early -- they should be set after a
device is completely instance_init'd, not halfway through init.
-- PMM
