On 24.04.2018 16:44, Igor Mammedov wrote:
> On Tue, 24 Apr 2018 15:41:23 +0200
> David Hildenbrand <da...@redhat.com> wrote:
>
>> On 24.04.2018 15:31, Igor Mammedov wrote:
>>> On Mon, 23 Apr 2018 14:52:37 +0200
>>> David Hildenbrand <da...@redhat.com> wrote:
>>>
>>>>>
>>>>>> + /* we will need a new memory slot for kvm and vhost */
>>>>>> + if (kvm_enabled() && !kvm_has_free_slot(machine)) {
>>>>>> + error_setg(errp, "hypervisor has no free memory slots left");
>>>>>> + return;
>>>>>> + }
>>>>>> + if (!vhost_has_free_slot()) {
>>>>>> + error_setg(errp, "a used vhost backend has no free memory slots
>>>>>> left");
>>>>>> + return;
>>>>>> + }
>>>>> move these checks to pre_plug time
>>>>>
>>>>>> +
>>>>>> + memory_region_add_subregion(&hpms->mr, addr - hpms->base, mr);
>>>>> missing vmstate registration?
>>>>
>>>> Missed this one: To be called by the caller. Important because e.g. for
>>>> virtio-pmem we don't want this (I assume :) ).
>>> if pmem isn't on shared storage, then We'd probably want to migrate
>>> it as well, otherwise target would experience data loss.
>>> Anyways, I'd just reat it as normal RAM in migration case
>>
>> Yes, if we realize that all MemoryDevices need this call, we can move it
>> to that place, too.
>>
>> Wonder if we might want to make this configurable for virtio-pmem later
>> on (via a flag or sth like that).
> I don't see any reason why we wouldn't like it to be migrated,
> it's the same as nvdimm but with another qemu:guest ABI
> and async flush instead of sync one we have with nvdimm.
>
Didn't you just mention "shared storage" ? :)
Anyhow, I leave such stuff to Pankaj to figure out. I remember him
working on some page cache details. Once clarified, this is easily
refactored later on.
--
Thanks,
David / dhildenb
