[dpdk-dev] [PATCH v3 3/7] net/virtio_user: move vhost user specific code

Tan, Jianfeng jianfeng.tan at intel.com
Wed Jan 4 07:46:34 CET 2017

Hi Yuanhan,

> -----Original Message-----
> From: Yuanhan Liu [mailto:yuanhan.liu at linux.intel.com]
> Sent: Wednesday, January 4, 2017 2:03 PM
> To: Tan, Jianfeng
> Cc: dev at dpdk.org; Yigit, Ferruh; Liang, Cunming
> Subject: Re: [PATCH v3 3/7] net/virtio_user: move vhost user specific code
> On Wed, Jan 04, 2017 at 03:59:22AM +0000, Jianfeng Tan wrote:
> > To support vhost kernel as the backend of net_virtio_user in coming
> > patches, we move vhost_user specific structs and macros into
> > vhost_user.c, and only keep common definitions in vhost.h.
> >
> > Besides, remove VHOST_USER_MQ feature check.
> Again, I have to ask, why? You don't only remove the check, also, you
> removed this feature setting, which seems to break the MQ support?

I have answered it here:

To be more clear, VHOST_USER_MQ is a not-well-defined macro: #define VHOST_USER_MQ (1ULL << VHOST_USER_F_PROTOCOL_FEATURES),
which is a feature bit in vhost user protocol.

According to QEMU/ docs/specs/vhost-user.txt, "If VHOST_USER_F_PROTOCOL_FEATURES has not been negotiated, the ring is initialized in an enabled state. "

But our DPDK vhost library does not take care of this feature bit. Just make this as default: the ring is initialized in an disabled state. And our virtio_user with vhost-user does send VHOST_USER_SET_VRING_ENABLE to enable each queue pair.

So I think it's not necessary to add it back.

How do you think?


> 	--yliu

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