Re: [PATCH v6 0/4] Add a vhost RPMsg API

From: Vincent Whitchurch <vincent.whitchurch@axis.com>
To: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Cc: Arnaud POULIQUEN <arnaud.pouliquen@st.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"linux-remoteproc@vger.kernel.org"
	<linux-remoteproc@vger.kernel.org>,
	"virtualization@lists.linux-foundation.org" 
	<virtualization@lists.linux-foundation.org>,
	"sound-open-firmware@alsa-project.org" 
	<sound-open-firmware@alsa-project.org>,
	Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>,
	Liam Girdwood <liam.r.girdwood@linux.intel.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Jason Wang <jasowang@redhat.com>,
	Ohad Ben-Cohen <ohad@wizery.com>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Mathieu Poirier <mathieu.poirier@linaro.org>, <kishon@ti.com>
Subject: Re: [PATCH v6 0/4] Add a vhost RPMsg API
Date: Thu, 17 Sep 2020 10:36:44 +0200	[thread overview]
Message-ID: <20200917083644.66yjer4zvoiftrk3@axis.com> (raw)
In-Reply-To: <20200917054705.GA11491@ubuntu>

On Thu, Sep 17, 2020 at 07:47:06AM +0200, Guennadi Liakhovetski wrote:
> On Tue, Sep 15, 2020 at 02:13:23PM +0200, Arnaud POULIQUEN wrote:
> > So i would be agree with Vincent[2] which proposed to switch on a RPMsg API
> > and creating a vhost rpmsg device. This is also proposed in the 
> > "Enhance VHOST to enable SoC-to-SoC communication" RFC[3].
> > Do you think that this alternative could match with your need?
> 
> As I replied to Vincent, I understand his proposal and the approach taken 
> in the series [3], but I'm not sure I agree, that adding yet another 
> virtual device / driver layer on the vhost side is a good idea. As far as 
> I understand adding new completely virtual devices isn't considered to be 
> a good practice in the kernel. Currently vhost is just a passive "library" 
> and my vhost-rpmsg support keeps it that way. Not sure I'm in favour of 
> converting vhost to a virtual device infrastructure.

I know it wasn't what you meant, but I noticed that the above paragraph
could be read as if my suggestion was to convert vhost to a virtual
device infrastructure, so I just want to clarify that that those are not
related.  The only similarity between what I suggested in the thread in
[2] and Kishon's RFC in [3] is that both involve creating a generic
vhost-rpmsg driver which would allow the RPMsg API to be used for both
sides of the link, instead of introducing a new API just for the server
side.  That can be done without rewriting drivers/vhost/.

> > [1]. https://patchwork.kernel.org/project/linux-remoteproc/list/?series=338335 
> > [2]. https://www.spinics.net/lists/linux-virtualization/msg44195.html
> > [3]. https://www.spinics.net/lists/linux-remoteproc/msg06634.html  