Hi Tetsuya,

With current your implementation, when 'virtual' virtio-net PMD is used,
'phys_addr' will be virtual address in EAL layer.

struct rte_memseg {
         phys_addr_t phys_addr;      /**< Start physical address. */
         union {
                 void *addr;         /**< Start virtual address. */
                 uint64_t addr_64;   /**< Makes sure addr is always 64
bits */
         };
         .......
};

It's not true. It does not effect EAL layer at all. Just fill virtual 
address in virtio PMD when:
1). set_base_addr;
2). preparing RX's descriptors;
3). transmitting packets, CVA is filled in TX's descriptors;
4). in TX and CQ's header, CVA is used.

How about choosing it in virtio-net PMD?

My current implementation works as you say.

(In the case of 'virtual', just use 'addr' instead of using 'phys_addr'.)
For example, port0 may use physical address, but port1 may use virtual
address.

With this, of course, we don't have an issue with 'physical' virtio-net PMD.
Also, with 'virtual' virtio-net PMD, we can use virtual address and fd
that represents the big virtual address space.
(TODO: Need to change rte_memseg and EAL to keep fd and offset?)

I suppose you mean that when initializing memory, just maintain one fd 
in the end, and
mmap all memsegs inside it. This sounds like a good idea to solve the 
limitation of
VHOST_MEMORY_MAX_NREGIONS.

Besides, Sergio and I are discussing about using VA instead of PA in 
VFIO to avoid the
requirement of physical-config for physical devices.


Thanks,
Jianfeng

Then, you don't worry about VHOST_MEMORY_MAX_NREGIONS, because we have
only one fd.

quoted

b. containers without root privilege
No need to worry about this problem, because it lacks of privilege to
construct physical-contiguous memory.

Yes, we cannot run 'physical' PMDs in this type of container.
Anyway, I will check it more, if we really need it.

Thanks,
Tetsuya