[dpdk-dev] [PATCH] doc: note a pitfall on reconnect feature

[dpdk-dev] [PATCH] doc: note a pitfall on reconnect feature

[Yuanhan Liu]

The vhost feature negotiation only happens at virtio reset stage, say
when a virtio-net device is firstly initiated, or when DPDK virtio PMD
initiates. That means, if vhost APP restarts after the negotiation and
reconnects, the feature negotiation process will not be triggered again,
meaning the info is lost. To make reconnect work, QEMU simply saves
the negotiated features before the restart and restores it afterwards.

Therefore, the vhost supported features must be exactly the same before
and after the restart. For example, if TSO is disabled and then enabled,
nothing will work and issues undefined might happen.

Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
---

I just put the part "people should not do this" into the doc, and I'm
not quite sure I need put the "why" part there or not.
---
 doc/guides/prog_guide/vhost_lib.rst | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/doc/guides/prog_guide/vhost_lib.rst b/doc/guides/prog_guide/vhost_lib.rst
index 14d5e67..6b0c6b2 100644
--- a/doc/guides/prog_guide/vhost_lib.rst
+++ b/doc/guides/prog_guide/vhost_lib.rst
@@ -189,7 +189,12 @@ vhost-user implementation has two options:
   When the DPDK vhost-user application restarts, DPDK vhost-user will try to
   connect to the server again. This is how the "reconnect" feature works.
 
-  Note: the "reconnect" feature requires **QEMU v2.7** (or above).
+  .. Note::
+     * The "reconnect" feature requires **QEMU v2.7** (or above).
+
+     * The vhost supported features must be exactly the same before and
+       after the restart. For example, if TSO is disabled and then enabled,
+       nothing will work and issues undefined might happen.
 
 No matter which mode is used, once a connection is established, DPDK
 vhost-user will start receiving and processing vhost messages from QEMU.
-- 
1.9.0

[dpdk-dev] [PATCH RFC] maintainers: add git tree for virtio/vhost

[Yuanhan Liu]

Add a git tree line for the virtio/vhost section, to make an explicit
statement that the developers are suggested to make patches based on
that tree.

Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
---
 MAINTAINERS | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 9c76352..433ddd8 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -356,6 +356,7 @@ F: doc/guides/nics/qede.rst
 RedHat virtio
 M: Huawei Xie <huawei.xie@intel.com>
 M: Yuanhan Liu <yuanhan.liu@linux.intel.com>
+T: git://dpdk.org/next/dpdk-next-virtio
 F: drivers/net/virtio/
 F: doc/guides/nics/virtio.rst
 F: lib/librte_vhost/
@@ -371,6 +372,7 @@ F: doc/guides/nics/vmxnet3.rst
 Vhost PMD
 M: Tetsuya Mukawa <mukawa@igel.co.jp>
 M: Yuanhan Liu <yuanhan.liu@linux.intel.com>
+T: git://dpdk.org/next/dpdk-next-virtio
 F: drivers/net/vhost/
 
 PCAP PMD
-- 
1.9.0

Re: [dpdk-dev] [PATCH RFC] maintainers: add git tree for virtio/vhost

[Thomas Monjalon]

2016-07-19 12:17, Yuanhan Liu:
> Add a git tree line for the virtio/vhost section, to make an explicit
> statement that the developers are suggested to make patches based on
> that tree.
> 
> Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>

Acked-by: Thomas Monjalon <thomas.monjalon@6wind.com>

Applied, thanks for your work on next-virtio

Re: [dpdk-dev] [PATCH] doc: note a pitfall on reconnect feature

[Mcnamara, John]

> -  Note: the "reconnect" feature requires **QEMU v2.7** (or above).
> +  .. Note::
> +     * The "reconnect" feature requires **QEMU v2.7** (or above).
> +
> +     * The vhost supported features must be exactly the same before and
> +       after the restart. For example, if TSO is disabled and then
> enabled,
> +       nothing will work and issues undefined might happen.

s/ issues undefined / undefined issues /

Apart from that:

Acked-by: John McNamara <john.mcnamara@intel.com>

Re: [dpdk-dev] [PATCH] doc: note a pitfall on reconnect feature

[Yuanhan Liu]

On Tue, Jul 19, 2016 at 01:57:11PM +0000, Mcnamara, John wrote:
> > -  Note: the "reconnect" feature requires **QEMU v2.7** (or above).
> > +  .. Note::
> > +     * The "reconnect" feature requires **QEMU v2.7** (or above).
> > +
> > +     * The vhost supported features must be exactly the same before and
> > +       after the restart. For example, if TSO is disabled and then
> > enabled,
> > +       nothing will work and issues undefined might happen.
> 
> s/ issues undefined / undefined issues /

Thomas, mind to fix it while apply?

> Apart from that:
> 
> Acked-by: John McNamara <john.mcnamara@intel.com>

Thanks!

	--yliu

Re: [dpdk-dev] [PATCH] doc: note a pitfall on reconnect feature

[Thomas Monjalon]

2016-07-20 09:08, Yuanhan Liu:
> On Tue, Jul 19, 2016 at 01:57:11PM +0000, Mcnamara, John wrote:
> > > -  Note: the "reconnect" feature requires **QEMU v2.7** (or above).
> > > +  .. Note::
> > > +     * The "reconnect" feature requires **QEMU v2.7** (or above).
> > > +
> > > +     * The vhost supported features must be exactly the same before and
> > > +       after the restart. For example, if TSO is disabled and then
> > > enabled,
> > > +       nothing will work and issues undefined might happen.
> > 
> > s/ issues undefined / undefined issues /
> 
> Thomas, mind to fix it while apply?

Yes

> > Apart from that:
> > 
> > Acked-by: John McNamara <john.mcnamara@intel.com>
> 
> Thanks!

Applied, thanks