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Date: Wed, 16 Dec 2015 20:08:17 +0800
From: Yuanhan Liu <yuanhan.liu@linux.intel.com>
To: Pavel Fedin <p.fedin@samsung.com>
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Cc: dev@dpdk.org, 'Victor Kaplansky' <victork@redhat.com>
Subject: Re: [dpdk-dev] [PATCH 0/4 for 2.3] vhost-user live migration support
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On Wed, Dec 16, 2015 at 02:57:15PM +0300, Pavel Fedin wrote:
>  Hello!
> 
> > I can reproduce your issue on my side with above patch (and only when
> > F_GUEST_ANNOUNCE is not set at DPDK vhost lib). TBH, I don't know
> > why that happened, the cause could be subtle, and I don't think it's
> > worthwhile to dig it, especially it's not the right way to do it.
> 
>  May be not right, may be it can be done... Actually, i found what was wrong. qemu tries to feed features back to vhost-user via
> VHOST_USER_SET_FEATURES, and DPDK barfs on the unknown bit. More tweaking is needed for qemu to do the trick correctly.
> 
> > So, would you please try to set the F_GUEST_ANNOUNCE flag on DPDK vhost
> > lib side, as my early diff showed and have another test?
> 
>  Tried it, works fine, thank you.

Thanks for the test.

However, I'm more curious about the ping loss? Did you still see
that? And to be more specific, have the wireshark captured the
GRAP from the guest?  And what's the output of 'grep virtio /proc/interrupts'
inside guest?

	--yliu


>  I have almost implemented the workaround in qemu... However now i start to think that you are right. Theoretically, the application
> may want to suppress GUEST_ANNOUNCE for some reason. So, let it stay this way. Please include this bit into your v2.
> 
> Kind regards,
> Pavel Fedin
> Expert Engineer
> Samsung Electronics Research center Russia
>