From mboxrd@z Thu Jan  1 00:00:00 1970
From: Yuanhan Liu <yliu@fridaylinux.org>
Subject: Re: [PATCH] examples/vhost_scsi: drop unimplemented
 EVENT_IDX feature bit
Date: Thu, 1 Feb 2018 22:47:42 +0800
Message-ID: <20180201144742.GR29540@yliu-mob>
References: <20180131174828.6936-1-stefanha@redhat.com>
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Cc: dev@dpdk.org, Junjie Chen <junjie.j.chen@intel.com>,
 Changpeng Liu <changpeng.liu@intel.com>,
 Maxime Coquelin <maxime.coquelin@redhat.com>
To: Stefan Hajnoczi <stefanha@redhat.com>,
 Thomas Monjalon <thomas@monjalon.net>
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On Wed, Jan 31, 2018 at 05:48:28PM +0000, Stefan Hajnoczi wrote:
> The vhost_scsi example application negotiates the
> VIRTIO_RING_F_EVENT_IDX feature bit but does not honor it when accessing
> vrings.
> 
> In particular, commit e37ff954405addb8ea422426a2d162d00dcad196 ("vhost:
> support virtqueue interrupt/notification suppression") broke vring call
> because vq->last_used_idx is never updated by vhost_scsi.  The
> vq->last_used_idx field is not even available via the librte_vhost
> public API, so VIRTIO_RING_F_EVENT_IDX is currently only usable by the
> built-in virtio_net.c driver in librte_vhost.
> 
> This patch drops VIRTIO_RING_F_EVENT_IDX from vhost_scsi so that vring
> call works again.
> 
> Cc: Changpeng Liu <changpeng.liu@intel.com>
> Cc: Junjie Chen <junjie.j.chen@intel.com>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

Acked-by: Yuanhan Liu <yliu@fridaylinux.org>

Thanks.

	--yliu
> ---
>  examples/vhost_scsi/vhost_scsi.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/examples/vhost_scsi/vhost_scsi.c b/examples/vhost_scsi/vhost_scsi.c
> index da01ad378..3cb4383e9 100644
> --- a/examples/vhost_scsi/vhost_scsi.c
> +++ b/examples/vhost_scsi/vhost_scsi.c
> @@ -21,7 +21,6 @@
>  #include "scsi_spec.h"
>  
>  #define VIRTIO_SCSI_FEATURES ((1 << VIRTIO_F_NOTIFY_ON_EMPTY) |\
> -			      (1 << VIRTIO_RING_F_EVENT_IDX) |\
>  			      (1 << VIRTIO_SCSI_F_INOUT) |\
>  			      (1 << VIRTIO_SCSI_F_CHANGE))
>  
> -- 
> 2.14.3