From: David Marchand <david.marchand@6wind.com>
Subject: Re: [PATCH v6 3/3] ivshmem: add check on protocol version in QEMU
Date: Thu, 25 Sep 2014 10:38:40 +0200
Message-ID: <5423D490.7050306@6wind.com>
References: <1410167870-680-1-git-send-email-david.marchand@6wind.com> <1410167870-680-4-git-send-email-david.marchand@6wind.com> <20140908094948.GB457@redhat.com> <20140923155831.GB3150@stefanha-thinkpad.redhat.com>
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Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org, pbonzini@redhat.com,
	claudio.fontana@huawei.com, jani.kokkonen@huawei.com,
	eblake@redhat.com, cam@cs.ualberta.ca, armbru@redhat.com,
	arei.gonglei@huawei.com, mkletzan@redhat.com
To: Stefan Hajnoczi <stefanha@gmail.com>,
	"Michael S. Tsirkin" <mst@redhat.com>
In-Reply-To: <20140923155831.GB3150@stefanha-thinkpad.redhat.com>
Sender: kvm-owner@vger.kernel.org

On 09/23/2014 05:58 PM, Stefan Hajnoczi wrote:
> I'm not sure a full-fledged feature negotiation system is needed.  The
> ivshmem protocol is local to the host and all participants are under
> control of the administrator.
>
> I suggested a protocol version to protect against misconfiguration.  For
> example, building QEMU from source but talking to an outdated ivhsmem
> server that is still running from before.
>
> Remember that ivshmem-server and QEMU are shipped together by the
> distro.  So in 99% of the cases they will have the same version anyway.
> But we want to protect against rare misconfiguration that break things
> (user mixing and matching incompatible software).

Ok, so how about keeping with this simple mechanism at the moment ?

If this versionning system is too limited in the future, I think we will 
need a global rework on the protocol, anyway.


-- 
David Marchand