Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
---
 docs/news.xml | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/docs/news.xml b/docs/news.xml
index 7ef18cf7b8..37b7fd9bba 100644
--- a/docs/news.xml
+++ b/docs/news.xml
@@ -114,6 +114,17 @@
           malfunctioning VM could affect all those running on the same host.
         </description>
       </change>
+      <change>
+        <summary>
+          qemu: Support migration with SLIRP interface
+        </summary>
+        <description>
+          As <code>libslirp</code> evolves, so does QEMU. The recent change is
+          that instead of peer-to-peer connection between QEMU and
+          <code>slirp-helper</code> process a separate D-BUS bus is created.
+          This enables QEMU to migrate with a SLIRP interface.
+        </description>
+      </change>
     </section>
     <section title="Bug fixes">
       <change>
-- 
2.24.1

On Wed, 2020-04-01 at 18:23 +0200, Michal Privoznik wrote:
> +      <change>
> +        <summary>
> +          qemu: Support migration with SLIRP interface
> +        </summary>
> +        <description>
> +          As <code>libslirp</code> evolves, so does QEMU. The recent change is
> +          that instead of peer-to-peer connection between QEMU and
> +          <code>slirp-helper</code> process a separate D-BUS bus is created.
> +          This enables QEMU to migrate with a SLIRP interface.
> +        </description>
> +      </change>

This looks reasonable enough to me, so

  Reviewed-by: Andrea Bolognani <abologna@redhat.com>

but let's maybe wait until tomorrow to push, in order to give
Marc-André a chance to speak his mind.

-- 
Andrea Bolognani / Red Hat / Virtualization

Hi

On Wed, Apr 1, 2020 at 6:40 PM Andrea Bolognani <abologna@redhat.com> wrote:
>
> On Wed, 2020-04-01 at 18:23 +0200, Michal Privoznik wrote:
> > +      <change>
> > +        <summary>
> > +          qemu: Support migration with SLIRP interface
> > +        </summary>
> > +        <description>
> > +          As <code>libslirp</code> evolves, so does QEMU. The recent change is
> > +          that instead of peer-to-peer connection between QEMU and
> > +          <code>slirp-helper</code> process a separate D-BUS bus is created.
> > +          This enables QEMU to migrate with a SLIRP interface.
> > +        </description>
> > +      </change>
>
> This looks reasonable enough to me, so
>
>   Reviewed-by: Andrea Bolognani <abologna@redhat.com>
>
> but let's maybe wait until tomorrow to push, in order to give
> Marc-André a chance to speak his mind.

Thanks. That's quite accurate, but it may be misinterpreted:

Networking data is still going through a 1-1 dgram unix socket.

D-Bus bus is used to communicate with the helper for RPC/management,
including migration.

After discussions, we decided to switch to a bus, as it permits other
tools, such as libvirt or others, to interact with the helpers easily.
A bus topology reduces the overall complexity for implementation and
debugging. This should slowly become the RPC standard for
"multi-process qemu"  in general. So libvirt will need a single
connection to the bus, and can then talk to the various helper
processes. Similarly for qemu or third-party (with security
restrictions).

Since the p2p dbus support was never actually used, I am not sure we
need to explain that there was a transition. Let me suggest:

qemu: Support migration with SLIRP helper interface

With QEMU 5.0, a new D-Bus backend allows migration of external
processes. When needed, libvirt will start a per-vm D-Bus bus, and
migrate the slirp-helper along with QEMU.

my 2c

On 1. 4. 2020 19:21, Marc-André Lureau wrote:
> 

Cool, thanks for your input. I'm putting you as the original author of
the text, putting Andrea's reviewed-by and pushing. Thanks!

Michal

On Wed, 2020-04-01 at 19:21 +0200, Marc-André Lureau wrote:
> Let me suggest:
> 
> qemu: Support migration with SLIRP helper interface
> 
> With QEMU 5.0, a new D-Bus backend allows migration of external
> processes. When needed, libvirt will start a per-vm D-Bus bus, and
> migrate the slirp-helper along with QEMU.

*per-VM

Aside from that nit, Marc-André's version looks good to me.

-- 
Andrea Bolognani / Red Hat / Virtualization