Il 29/05/2013 06:41, Amos Kong ha scritto:
On Tue, May 28, 2013 at 01:15:57PM +0200, Paolo Bonzini wrote:
Il 28/05/2013 13:00, Amos Kong ha scritto:
Recent virtio refactoring in QEMU made virtio-bus become the parent bus of scsi-bus, and virtio-bus doesn't have get_fw_dev_path implementation, so redundant typename will be added to fw_dev_path. It causes that bootindex parameter of scsi device doesn't work.
This patch changes qdev_get_fw_dev_path_helper() to add nothing if implemented get_fw_dev_path() returns NULL.
Signed-off-by: Amos Kong akong@redhat.com
v2: only add nothing to fw_dev_path when get_fw_dev_path() is implemented and return NULL. then it will not effect other devices don't have get_fw_dev_path() implementation.
Hi Paolo,
To achieve the same result, you can simply ensure that all classes implement the method.
Do you mean if some classes didn't have an implement, I need to add a implement (just returns NULL) for all of them, then nothing will be added to fw_dev_path for those classes?
No, you can have an implementation in BusClass. See how device_class_init provides a default implementation for realize/unrealize, and do the same in bus_class_init.
Currently I'm sure 'typename' is redundant for virio-bus. 'typename' might be needed for other class (have no get_fw_dev_path implementation)
Applied patch v2, there are three conditions:
- implement get_fw_dev_path, return specific string, add to fw_dev_path (same as original)
- don't implement get_fw_dev_path, add typename to fw_dev_path. (same as original)
- implement get_fw_dev_path and return NULL, nothing is added to fw_dev_path (new behavior)
If some other class wants to add nothing to path, just define a method to return NULL.
The default implementation is just g_strdup(object_get_typename(OBJECT(dev))).
If we implement the method for all classes, the default implementation in qdev_get_fw_dev_path_helper() will not be called.
Yes, but we shouldn't implement the method for all classes. We should implement it just once in BusClass. Then the default implementation in qdev_get_fw_dev_path_helper() can be removed. It will live in BusClass instead
Paolo
Remember that if you do not specify a method in a BusClass's class_init function, it is inherited from the superclass.
Paolo