From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47616) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VLW4u-0002GT-G9 for qemu-devel@nongnu.org; Mon, 16 Sep 2013 06:30:54 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VLW4o-0000od-7K for qemu-devel@nongnu.org; Mon, 16 Sep 2013 06:30:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:30298) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VLW4n-0000oR-Vw for qemu-devel@nongnu.org; Mon, 16 Sep 2013 06:30:42 -0400 Message-ID: <5236DDC7.1010908@redhat.com> Date: Mon, 16 Sep 2013 12:30:31 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1379314227-8855-1-git-send-email-famz@redhat.com> <1379314227-8855-6-git-send-email-famz@redhat.com> <20130916085902.GA6005@redhat.com> <5236D318.4080206@redhat.com> <20130916095121.GD22783@T430s.nay.redhat.com> <5236D8EB.9060700@redhat.com> <20130916101415.GH6005@redhat.com> <5236DB0E.5040302@redhat.com> <20130916102131.GI6005@redhat.com> In-Reply-To: <20130916102131.GI6005@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v10 5/8] module: implement module loading List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Daniel P. Berrange" Cc: peter.maydell@linaro.org, famz@redhat.com, mjt@tls.msk.ru, qemu-devel@nongnu.org, alex@alex.org.uk, vilanova@ac.upc.edu, rth@twiddle.net Il 16/09/2013 12:21, Daniel P. Berrange ha scritto: > On Mon, Sep 16, 2013 at 12:18:54PM +0200, Paolo Bonzini wrote: >> Il 16/09/2013 12:14, Daniel P. Berrange ha scritto: >>> On Mon, Sep 16, 2013 at 12:09:47PM +0200, Paolo Bonzini wrote: >>>> Il 16/09/2013 11:51, Fam Zheng ha scritto: >>>>> On Mon, 09/16 11:44, Paolo Bonzini wrote: >>>>>> Il 16/09/2013 10:59, Daniel P. Berrange ha scritto: >>>>>>>> The init function of dynamic module is no longer with >>>>>>>> __attribute__((constructor)) as static linked version, and need to be >>>>>>>> explicitly called once loaded. The function name is mangled with per >>>>>>>> configure fingerprint as: >>>>>>>> >>>>>>>> init_$(date +%s$$$RANDOM) >>>>>> >>>>>> Does this work for a module that calls module_init multiple times? >>>>> >>>>> Why should a module calls module_init, instead of the main function? >>>> >>>> I think you mean "why should a module calls register_module_init", and I >>>> agree that with this patch a module will not call register_module_init. >>>> >>>> But a module is still using the module_init macro. >>>> >>>> With this patch, a module will not be able to use the module_init macro >>>> twice. I am not sure this is an acceptable limitation, especially if we >>>> do not have a dependency system within modules and/or load them with >>>> G_MODULE_LOCAL/RTLD_LOCAL. >>> >>> Why would a module ever want to use the module_init macro twice ? >> >> Because our coding standard is to have each source file do its own >> one-time initialization, using static functions and an invocation of >> module_init per source file. > > Is there ever a case where two source files, each using module_init > will be compiled into the same .so loadable module. Looking at the > uses of block_init(), I don't see any obvious candidates for trouble, > all uses look like they'd be going into separate .so files. Without inter-module exports, all of SPICE probably would have to be in a single .so file. This includes spice-qemu-char.c and hw/display/qxl.c, both of which use type_init. If we use G_MODULE_GLOBAL as a primitive system for intermodule exports, then indeed this is a much smaller problem, but then we need a dependency system. But I'm almost sure that Windows and maybe Darwin lack support for the equivalent of G_MODULE_GLOBAL. BTW, we need a buildbot for the static linking case, otherwise as modules become more widespread, we'll have hard to detect bugs due to duplicate symbols. Paolo