Re: [PATCH v1 0/2] Virtio-net PMD Extension to work on host

[Tetsuya Mukawa <mukawa@igel.co.jp>]

On 2015/12/28 20:06, Tetsuya Mukawa wrote:
> On 2015/12/24 23:05, Tan, Jianfeng wrote:
>> Hi Tetsuya,
>>
>> After several days' studying your patch, I have some questions as follows:
>>
>> 1. Is physically-contig memory really necessary?
>> This is a too strong requirement IMHO. IVSHMEM doesn't require this in its original meaning. So how do you think of
>> Huawei Xie's idea of using virtual address for address translation? (In addition, virtual address of mem_table could be
>> different in application and QTest, but this can be addressed because SET_MEM_TABLE msg will be intercepted by
>> QTest)
> Hi Jianfeng,
>
> Thanks for your suggestion.
> Huawei's idea may solve contig-mem restriction.
> Let me have time to check it more.

Hi Jianfeng,

I made sure we can remove the restriction with Huawei's idea.
One thing I concern is below.
If we don't use contiguous memory, this PMD will not work with other
'physical' PMDs like e1000 PMD, virtio-net PMD, and etc.
(This is because allocated memory may not  be physically contiguous.)

One of examples is that if we implement like above, in QEMU guest, we
can handle a host NIC directly, but in container, we will not be able to
handle the device.
This will be a restriction for this virtual addressing changing.

Do you know an use case that the user wants to handle 'physical' PMD and
'virtual' virtio-net PMD together?

Tetsuya,