Re: [Qemu-devel] [PATCH qemu v7 06/14] spapr_iommu: Introduce "enabled" state for TCE table

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 05/26/2015 10:50 PM, Paolo Bonzini wrote:
>
>
> On 26/05/2015 14:33, Alexey Kardashevskiy wrote:
>>
>>>>> If it's not true now that they can be unparented at any time like
>>>>> alias regions, we should probably try to make it true.
>>>>
>>>> Unfortunately it's not so easy...
>>
>>
>> Uff. Tricky :)
>>
>> memory_region_del_subregion() is not unparenting but just a wrapped
>> object_unref(), right?
>
> Right.  The problematic thing to do is explicit object_unparent followed
> by one of the following:
>
> 1) memory_region_init for the same memory region that has been unparented
>
> 2) g_free of some dynamically-allocated data structure that contained
> the memory region.
>
>> But since iommu MR are resolved dynamically, the
>> whole conversation we are having here now has nothing to do with my&Mike
>> concern what we can and cannot do with DMA windows here. Is this correct?
>
> I don't understand what you're asking here, sorry.


My initial concern was if I can or cannot do:

memory_region_init_iommu + memory_region_add_subregion
and
memory_region_del_subregion + object_unref

outside of init/realize/unrealize/finalize.

You said I cannot do unparenting but as I am not doing this (and I just do 
unref()) - I am fine. That's what I meant.




-- 
Alexey