Re: [Qemu-devel] [PATCH] migration: discard RAMBlocks of type ram_device

["Cédric Le Goater" <clg@kaod.org>]

On 04/12/2018 02:08 PM, Peter Maydell wrote:
> On 12 April 2018 at 12:53, Dr. David Alan Gilbert <dgilbert@redhat.com> wrote:
>> * Peter Maydell (peter.maydell@linaro.org) wrote:
>>> David suggested on IRC that we would want a flag on the ramblock
>>> for "not migratable", because there are other uses for "don't
>>> migrate this" than just "is this a ram device".
>>
>> My original suggestion to your series was with a flag, but I'd forgotten
>> about that by the time I'd made the suggestion to Cédric.
>> In your case would just adding an extra term to the
>> ram_block_is_migratable function work, or do you really need a flag?
> 
> I don't see how else you would identify the ram block that needs
> to be skipped. Also I think it's just better design to decouple
> the decision about "should we migrate this ram block" from the
> migration code itself, and push it up to the code layer that knows
> it's creating ram blocks that shouldn't be migrated.

Do you mean adding a new RAMBlock flag RAM_NON_MIGRATABLE 
in exec.c ? That would require to add an extra bool to the 
following functions :

	memory_region_init_ram_ptr()
	qemu_ram_alloc_from_ptr()
	qemu_ram_alloc_internal()

Would that be ok ? 

Thanks,

C.