[dpdk-dev] Regarding MMIO

Xie, Huawei huawei.xie at intel.com
Mon Oct 5 15:39:49 CEST 2015


On 10/5/2015 12:41 PM, Venkateswara Rao Dokku wrote:
> Thanks for the response Stephen.
>
> Are you referring to Virt-IO 0.9 in specific here in the response or for
> any Virt-IO versions in general?
>
> On Thu, Oct 1, 2015 at 8:12 PM, Stephen Hemminger <
> stephen at networkplumber.org> wrote:
>
>> On Thu, 1 Oct 2015 09:51:42 +0530
>> Venkateswara Rao Dokku <dvrao.584 at gmail.com> wrote:
>>
>>> Hi,
>>>
>>> If we go through the DPDK code it is observed that we are using MMIO for
>>> Virt-IO devices. But in the Virt-IO specification, it is written that
>> from
>>> Virt-IO 1.0 onwards only they are supporting MMIO, all previous versions
>>> uses Port IO for RX/TX notifications.
>>>
>>> So, If I use VirtIO 0.9, Can I get the MMIO based notifications for RX/TX
>>> or is it supported only for Virt-IO 1.0 onwards?
>>>
>> Although the virtio device will bind to the mmio address in some cases,
>> it does not use that. It uses i/o port access (see iopl) to activate
>> host.

Which is used depends on access time. Check the virtio 1.0 improvement
for mmio access.
http://events.linuxfoundation.org/sites/events/files/slides/misha2015-v1.pdf
Is there any special reason you want to use mmio based notification?

>
>



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