From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:33175) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RLfw6-0000HO-6N for qemu-devel@nongnu.org; Wed, 02 Nov 2011 14:53:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RLfw4-0007PC-Dx for qemu-devel@nongnu.org; Wed, 02 Nov 2011 14:53:18 -0400 Received: from thoth.sbs.de ([192.35.17.2]:21521) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RLfw4-0007Ol-1K for qemu-devel@nongnu.org; Wed, 02 Nov 2011 14:53:16 -0400 Message-ID: <4EB19183.2000704@siemens.com> Date: Wed, 02 Nov 2011 19:52:51 +0100 From: Jan Kiszka MIME-Version: 1.0 References: <4639B135-B96A-43A0-B4FA-6DDCBE3FBA92@suse.de> <4EB18172.1020905@adacore.com> <4EB18952.4080403@siemens.com> <4EB18C13.2030704@codemonkey.ws> <4EB18D1C.4090000@suse.de> <4EB18FFF.7010603@siemens.com> <4EB190DA.1010506@codemonkey.ws> In-Reply-To: <4EB190DA.1010506@codemonkey.ws> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] GSoC mentor summit QEMU users session List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: Peter Maydell , Alexander Graf , Fabien Chouteau , "qemu-devel@nongnu.org Developers" On 2011-11-02 19:50, Anthony Liguori wrote: > On 11/02/2011 01:46 PM, Jan Kiszka wrote: >> On 2011-11-02 19:34, Alexander Graf wrote: >>> Anthony Liguori wrote: >>>> On 11/02/2011 01:17 PM, Jan Kiszka wrote: >>>>> On 2011-11-02 18:44, Fabien Chouteau wrote: >>>>>> On 31/10/2011 14:12, Peter Maydell wrote: >>>>>>> On 29 October 2011 14:52, Alexander Graf wrote: >>>>>>>> A lot of people seem to also have code that doesn't make sense >>>>>>>> upstream, for example implementing a one-off device that only >>>>>>>> really matters for their own devboard which nobody else owns. >>>>>>>> For such cases, having a plugin framework would be handy. I >>>>>>>> interestingly enough got into the same discussion on LinuxCon >>>>>>>> with some QEMU downstreams. >>>>>>> >>>>>>> If we get the qdev rework done then I think we're probably in >>>>>>> a better position to have a plugin framework for devices. (There >>>>>>> are some issues about API and ABI stability guarantees, of course.) >>>>>>> >>>>>> >>>>>> Interesting, we have a "plug-in" implementation in our Qemu branch. It >>>>> >>>>> We have a "plugin" model here as well. It's really simple: the plugin is >>>>> loaded dynamically into the QEMU process and can access any global >>>>> function and variable. Of course, this breaks regularly. >>>> >>>> Yes, this is the Right Model. >>>> >>>> All of the work is in making the interfaces not break regularly. >>>> Loading a shared object is easy enough. >>> >>> I agree. In fact, we could even do it the same way as the kernel and >>> build all our internal hw pieces as shared objects. >>> >>> Then users who want to cut down QEMU can just remove .so files instead >>> of messing with the build system or code. >> >> We should also be able to establish an EXPORT_SYMBOL concept, ie. only >> export those functions that are supposed to be part of a component API. >> Will be some work initially, but should be off long term, both to QEMU >> in maintaining stable APIs and to external components in using the >> proper ones. > > Not at first. We don't need yet another interface that we have to try to > maintain. Until things stabilize internally, the module interface should be > completely unstable. For sure. It would not work out of the box anyway as way too many functions would have to be marked - and way too much code refactored first. We could start with a MAY_BECOME_API_SYMBOL marker that does nothing except commenting the plan. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux