[dpdk-dev] vhost-user technical isssues

[Xie, Huawei]

Hi Tetsuya:
There are two major technical issues in my mind for vhost-user implementation.

1) memory region map
Vhost-user passes us file fd and offset for each memory region. Unfortunately the mmap offset is "very" wrong. I discovered this issue long time ago, and also found
that I couldn't mmap the huge page file even with correct offset(need double check).
Just now I find that people reported this issue on Nov 3.
[Qemu-devel] [PULL 27/29] vhost-user: fix mmap offset calculation
Anyway, I turned to the same idea used in our DPDK vhost-cuse: only use the fd for region(0) to map the  whole file.
I think we should use this way temporarily to support qemu-2.1 as it has that bug.

2) what message is the indicator for vhost start/release?
Previously  for vhost-cuse, it has SET_BACKEND message.
What we should do for vhost-user?
SET_VRING_KICK for start?
What about for release?
Unlike the kernel virtio, the DPDK virtio in guest could be restarted. 

Thoughts?

-huawei