From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guennadi Liakhovetski Subject: Re: [PATCH v3 0/5] Add a vhost RPMsg API Date: Mon, 8 Jun 2020 12:15:27 +0200 Message-ID: <20200608101526.GD10562@ubuntu> References: <20200527180541.5570-1-guennadi.liakhovetski@linux.intel.com> <20200604151917-mutt-send-email-mst@kernel.org> <20200605063435.GA32302@ubuntu> <20200608073715.GA10562@ubuntu> <20200608091100.GC10562@ubuntu> <20200608051358-mutt-send-email-mst@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20200608051358-mutt-send-email-mst@kernel.org> Sender: kvm-owner@vger.kernel.org To: "Michael S. Tsirkin" Cc: kvm@vger.kernel.org, linux-remoteproc@vger.kernel.org, virtualization@lists.linux-foundation.org, sound-open-firmware@alsa-project.org, Pierre-Louis Bossart , Liam Girdwood , Jason Wang , Ohad Ben-Cohen , Bjorn Andersson , Mathieu Poirier List-Id: virtualization@lists.linuxfoundation.org On Mon, Jun 08, 2020 at 05:19:06AM -0400, Michael S. Tsirkin wrote: > On Mon, Jun 08, 2020 at 11:11:00AM +0200, Guennadi Liakhovetski wrote: > > Update: I looked through VirtIO 1.0 and 1.1 specs, data format their, > > including byte order, is defined on a per-device type basis. RPMsg is > > indeed included in the spec as device type 7, but that's the only > > mention of it in both versions. It seems RPMsg over VirtIO isn't > > standardised yet. > > Yes. And it would be very good to have some standartization before we > keep adding things. For example without any spec if host code breaks > with some guests, how do we know which side should be fixed? > > > Also it looks like newer interface definitions > > specify using "guest native endianness" for Virtual Queue data. > > They really don't or shouldn't. That's limited to legacy chapters. > Some definitions could have slipped through but it's not > the norm. I just quickly looked through the 1.1 spec and could > not find any instances that specify "guest native endianness" > but feel free to point them out to me. Oh, there you go. No, sorry, my fault, it's the other way round: "guest native" is for legacy and LE is for current / v1.0 and up. > > So > > I think the same should be done for RPMsg instead of enforcing LE? > > That makes hardware implementations as well as any cross-endian > hypervisors tricky. Yes, LE it is then. And we need to add some text to the spec. In theory there could be a backward compatibility issue - in case someone was already using virtio_rpmsg_bus.c in BE mode, but I very much doubt that... Thanks Guennadi