Hi, yuanhan:
> -----Original Message-----
> From: Yuanhan Liu [mailto:yuanhan....@linux.intel.com]
> Sent: Thursday, April 27, 2017 4:12 PM
> To: Yang, Zhiyong <zhiyong.y...@intel.com>
> Cc: dev@dpdk.org; maxime.coque...@redhat.com; Loftus, Ciara
> <ciara.lof...@intel.com>
> Subject: Re: [PATCH] vhost: fix MQ fails to startup
>
> On Thu, Apr 27, 2017 at 02:34:53PM +0800, Zhiyong Yang wrote:
> > vhost since dpdk17.02 + qemu2.7 and above will cause failures of new
> > connection when negotiating to set MQ. (one queue pair works
> > well).Because there exist some bugs in qemu code when introducing
> > VHOST_USER_PROTOCOL_F_REPLY_ACK to qemu. when dealing with the
> vhost
> > message VHOST_USER_SET_MEM_TABLE for the second time, qemu indeed
> > doesn't send the messge (The message needs to be sent only once)but
> > still will be waiting for dpdk's reply ack, then, qemu is always
> > freezing. DPDK code works in the right way. But the feature
> > VHOST_USER_PROTOCOL_F_REPLY_ACK has to be disabled by default at the
> > dpdk side in order to avoid the feature support of DPDK + qemu at the
> > same time. if doing like that, MQ can works well.
> ...
> > Once Qemu bugs
> > have been fixed and upstreamed, we can enable it.
>
> As I have said, we should not enable it again, because there are already few
> buggy QEMU releases out. We should make sure DPDK also works well with
> them.
Ok.
>
> > Fixes: 73c8f9f69c6c("vhost: introduce reply ack feature")
>
> That commit does nothing wrong. It's QEMU being buggy. That said, I will not
> add such fixline. I will also use "workaround" instead of "fix" in the title.
>
Ok. I also think dpdk works in the right way. But I'm using "fix" in the title
here.
Your suggestion is good.
> Also, this patch should be backported to stable release. So, you should
> add:
> Cc: sta...@dpdk.org
>
Ok
> Besides, please reformat you commit log a bit. For example, add space after
> punctuation, use paragraph as possible, etc.
Ok.
>
> >
> > Reported-by: Loftus, Ciara <ciara.lof...@intel.com>
>
> No "," is allowed.
>
Ok
> > Signed-off-by: Zhiyong Yang <zhiyong.y...@intel.com>
> > ---
> > lib/librte_vhost/vhost_user.h | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/lib/librte_vhost/vhost_user.h
> > b/lib/librte_vhost/vhost_user.h index 2ba22db..a3d2900 100644
> > --- a/lib/librte_vhost/vhost_user.h
> > +++ b/lib/librte_vhost/vhost_user.h
> > @@ -52,7 +52,7 @@
> > #define VHOST_USER_PROTOCOL_FEATURES ((1ULL <<
> VHOST_USER_PROTOCOL_F_MQ) | \
> > (1ULL <<
> VHOST_USER_PROTOCOL_F_LOG_SHMFD) |\
> > (1ULL <<
> VHOST_USER_PROTOCOL_F_RARP) | \
> > - (1ULL <<
> VHOST_USER_PROTOCOL_F_REPLY_ACK) | \
> > + (0ULL <<
> VHOST_USER_PROTOCOL_F_REPLY_ACK) | \
> > (1ULL <<
> VHOST_USER_PROTOCOL_F_NET_MTU))
>
> I think you might want to add a simple comment here, something like
>
> /*
> * disable REPLY_ACK feature to workaround the buggy QEMU
> implementation.
> * Proved buggy QEMU includes v2.7 - v2.9.
> */
>
> So, please send v2?
>
Ok.
I will send it later.
Zhiyong
> --yliu
