From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41596) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fQsEK-0006l9-00 for qemu-devel@nongnu.org; Thu, 07 Jun 2018 06:33:21 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fQsEI-0005oS-QS for qemu-devel@nongnu.org; Thu, 07 Jun 2018 06:33:19 -0400 Date: Thu, 7 Jun 2018 11:33:07 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Message-ID: <20180607103307.GI28827@redhat.com> Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= References: <20180603203412.11033-1-contrib@steffen-goertz.de> <20180604092008.GA13674@stefanha-x1.localdomain> <20180604101221.nhvjum467ier3txx@sirius.home.kraxel.org> <20180607102455.GD19032@stefanha-x1.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20180607102455.GD19032@stefanha-x1.localdomain> Subject: Re: [Qemu-devel] [RFC v3] qapi: command category to stimulate high-level machine devices List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi Cc: Gerd Hoffmann , Peter Maydell , Jim Mussared , Steffen =?utf-8?B?R8O2cnR6?= , QEMU Developers , Markus Armbruster , "open list:ARM" , Joel Stanley , Julia Suvorova On Thu, Jun 07, 2018 at 11:24:55AM +0100, Stefan Hajnoczi wrote: > On Mon, Jun 04, 2018 at 12:12:21PM +0200, Gerd Hoffmann wrote: > > On Mon, Jun 04, 2018 at 10:29:40AM +0100, Peter Maydell wrote: > > > On 4 June 2018 at 10:20, Stefan Hajnoczi wrote: > > > > Many of these inputs/outputs can be tied to an external UI. A degree of > > > > timing precision is required so that the UI is responsive, although > > > > cycle-accurate timing is not what I'd expect from QMP. > > > > > > Would we also be able to tie them to an internal UI, ie > > > something that appears as another view in the GTK/etc > > > UI frontends we have? > > > > Should be doable too. Basically a display device, which isn't a *real* > > display but the UI. Could show a rendering of the board, simliar to how > > web emulation environments are doing it. LED status could be rendered > > directly to the board. A virtual mouse could map mouse clicks to button > > presses. > > > > Doing more complex input that way (say a slider for the temperature > > sensor) isn't going to work very well though ... > > > > Sensor input in general is pretty much unsupported in qemu. > > For the micro:bit we've been thinking of a WebSocket monitor interface. > This way a web UI can work with both local and remote QEMU instances. > > For security reasons, the WebSocket cannot be the regular QMP monitor. FWIW, add ability to use websockets protocol over chardevs is fairly easy. We already have a QIOChannelWebsock for the VNC server, so it is just a little work to wire it into the chardev. If the -monitor / -qmp arg took a filename containing a whitelist of allowed monitor commands, you could indeed use the regular QMP monitor instead of writing something new. > A slimmed down monitor is required with a subset of QMP commands and > events. For example, users must not be able to migrate to an exec: > destination so we need to ban that command on the UI monitor :-). FWIW, you could use the "-sandbox spawn=off,elevateprivileges=off" arg to prevent ability of QEMU to fork/exec/setuid. Even if the monitor still allows it, it thus get blocked, albeit by immediately terminating the process. > Pros: > + Remote control is possible over sockets > (Important for hosting QEMU on a server. Nowadays this is becoming a > popular way to deliver emulation to users. They don't need to > install software locally.) > + UI is cleanly isolated from QEMU process > Cons: > - Binary or high-frequency I/O is a bad fit for a JSON WebSocket > interface > > I prefer the WebSocket route over creating a fake display that will not > be able to implement complex widgets well. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|