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Date: Wed, 25 Jul 2018 09:23:51 +0800
From: Tiwei Bie <tiwei.bie@intel.com>
To: Marvin Liu <yong.liu@intel.com>
Cc: dev@dpdk.org, maxime.coquelin@redhat.com, zhihong.wang@intel.com
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Subject: Re: [dpdk-dev] [PATCH] examples/vhost: fix qemu abort
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On Tue, Jul 24, 2018 at 11:16:49PM +0800, Marvin Liu wrote:
> When start vhost sample with builtin-net-driver argument, vhost feature
> bit will be zero. If VHOST_USER_F_PROTOCOL_FEATURES is not set, vhost
> net start will be failed in qemu. This occasion will cause device stop
> action was skipped. Consequently, same ioevent fd will be added second
> time after reload driver and then cause qemu abort. Add feature bit
> which has been supported by vhost library can fix this error.
>
> Fixes: ca059fa5 ("examples/vhost: demonstrate the new generic APIs")
It's a bug in QEMU, this is a workaround in DPDK.
So there is no need to fix any commit in DPDK.
>
> Signed-off-by: Marvin Liu <yong.liu@intel.com>
>
> diff --git a/examples/vhost/main.c b/examples/vhost/main.c
> index 2175c1186..44aec2f47 100644
> --- a/examples/vhost/main.c
> +++ b/examples/vhost/main.c
> @@ -1520,7 +1520,8 @@ main(int argc, char *argv[])
> }
>
> if (builtin_net_driver)
> - rte_vhost_driver_set_features(file, VIRTIO_NET_FEATURES);
There is no need to remove VIRTIO_NET_FEATURES
although it's defined to 0 (as it's helpful for
users to understand this example).
> + rte_vhost_driver_set_features(file,
> + 1ULL << VHOST_USER_F_PROTOCOL_FEATURES);
It's better to add some comments that this is
a workaround and why this workaround is needed.
>
> if (mergeable == 0) {
> rte_vhost_driver_disable_features(file,
> --
> 2.17.0
>