On 05/03/2025 13:13, Cédric Le Goater wrote:
> Joao,
>
> On 3/5/25 12:16, Joao Martins wrote:
>> On 14/02/2025 13:05, Cédric Le Goater wrote:
>>> +Kirti
>>> +Joao
>>>
>>> On 2/13/25 22:45, Alex Williamson wrote:
>>>>> +
>>>>> + /*
>>>>> + * Migration support
>>>>> + */
>>>>> + object_class_property_set_description(klass, /* 5.2 */
>>>>> +
>>>>> "x-pre-copy-dirty-page-tracking",
>>>>> + "Disable dirty pages tracking
>>>>> during iterative phase");
>>>>> + object_class_property_set_description(klass, /* 9.1 */
>>>>> + "x-device-dirty-page-tracking",
>>>>> + "Disable device dirty page
>>>>> tracking and use container-based dirty page tracking");
>>>> These are really debug as well, right? They just happen to be
>>>> migration related debug.
>>>
>>> I suppose so. I would rather keep them under the migration topic
>>> and add 'debug' in the comment.
>>>
>>> Changes :
>>>
>>> commit bb0990d1740f ("vfio: Change default dirty pages tracking behavior
>>> during migration")
>>> commit 30b916778517 ("vfio/common: Allow disabling device dirty page
>>> tracking")
>>>
>>> do not explicitly explain why these properties are useful in any way.
>>>
>>> Kirti, Joao, could you ?
>>
>> Sorry for the extreme delay but I was out travelling for the past 3 weeks for
>> vacation and work.
>>
>> The property is marked as x- but my intent was both debug/testing and to have
>> something that allows me to select the dirty tracker between device vs
>> platform
>> dirty tracker if something is wrong with say VF dirty tracker or if there's
>> some
>> limitations around it. These days we actually use it a lot as my default to
>> have
>> IOMMU dirty tracker in use. I wouldn't label it exclusively as '(debug)' just
>> yet.
>>
>> The precopy option might be to avoid dirty tracking at all and it's generally
>> useful when you don't have dirty tracking at all or say snapshots or 'offline
>> migration'. But I have never seen real use of it, or need for that matter,
>> except the early days of VFIO migration during testing.
>
> Could you please send a patch on top of :
>
> https://lore.kernel.org/qemu-devel/20250217173455.449983-1-...@redhat.com/
>
> This would be great to keep the information in the git history.
I'll send a patch shortly.
