From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57029) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VLqzV-0004M3-63 for qemu-devel@nongnu.org; Tue, 17 Sep 2013 04:50:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VLqzM-0003x1-8b for qemu-devel@nongnu.org; Tue, 17 Sep 2013 04:50:37 -0400 Received: from e23smtp04.au.ibm.com ([202.81.31.146]:59009) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VLqzL-0003wi-MT for qemu-devel@nongnu.org; Tue, 17 Sep 2013 04:50:28 -0400 Received: from /spool/local by e23smtp04.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 17 Sep 2013 18:50:23 +1000 Received: from d23relay03.au.ibm.com (d23relay03.au.ibm.com [9.190.235.21]) by d23dlp01.au.ibm.com (Postfix) with ESMTP id D02892CE8051 for ; Tue, 17 Sep 2013 18:50:20 +1000 (EST) Received: from d23av03.au.ibm.com (d23av03.au.ibm.com [9.190.234.97]) by d23relay03.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r8H8o9mk9437650 for ; Tue, 17 Sep 2013 18:50:10 +1000 Received: from d23av03.au.ibm.com (localhost [127.0.0.1]) by d23av03.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id r8H8oJmf002848 for ; Tue, 17 Sep 2013 18:50:19 +1000 Message-ID: <523817C9.3060502@linux.vnet.ibm.com> Date: Tue, 17 Sep 2013 16:50:17 +0800 From: Wenchao Xia 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> <5236DDC7.1010908@redhat.com> <20130916112917.GA21374@T430s.nay.redhat.com> In-Reply-To: <20130916112917.GA21374@T430s.nay.redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 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: famz@redhat.com Cc: peter.maydell@linaro.org, mjt@tls.msk.ru, qemu-devel@nongnu.org, alex@alex.org.uk, Paolo Bonzini , vilanova@ac.upc.edu, rth@twiddle.net 于 2013/9/16 19:29, Fam Zheng 写道: > On Mon, 09/16 12:30, Paolo Bonzini wrote: >> 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$$$RANDOM) >>>>>>>> Does this work for a module that calls module_init multiple times? >>>>>>> Why should a module calls module_init, instead of the main function? >>>>>> I think you mean "why should a module calls register_module_init", and I >>>>>> agree that with this patch a module will not call register_module_init. >>>>>> >>>>>> But a module is still using the module_init macro. >>>>>> >>>>>> With this patch, a module will not be able to use the module_init macro >>>>>> twice. I am not sure this is an acceptable limitation, especially if we >>>>>> do not have a dependency system within modules and/or load them with >>>>>> G_MODULE_LOCAL/RTLD_LOCAL. >>>>> Why would a module ever want to use the module_init macro twice ? >>>> Because our coding standard is to have each source file do its own >>>> one-time initialization, using static functions and an invocation of >>>> module_init per source file. >>> Is there ever a case where two source files, each using module_init >>> will be compiled into the same .so loadable module. Looking at the >>> uses of block_init(), I don't see any obvious candidates for trouble, >>> all uses look like they'd be going into separate .so files. >> Without inter-module exports, all of SPICE probably would have to be in >> a single .so file. This includes spice-qemu-char.c and >> hw/display/qxl.c, both of which use type_init. >> >> If we use G_MODULE_GLOBAL as a primitive system for intermodule exports, >> then indeed this is a much smaller problem, but then we need a >> dependency system. But I'm almost sure that Windows and maybe Darwin >> lack support for the equivalent of G_MODULE_GLOBAL. >> > An idea for single .so file: > - before loads a .so, an empty initializer list is created. > - module_init adds a __attribute__((constructor)) function, which appends > its real initializer to the initializer list. So this function is > automatically called after dlopen(). > - make init_$(date +%s$$$RANDOM) a dummy symbol. > - module_load first checks the presense of the symbol, if yes, call the > functions in the initializer list. Else clean up and unload .so. > > Does this enable multiple calls of module_init()? > I like this way since it keeps the old init behavior which delayed the work with a list. > OTOH. As for multiple spice modules, is it possible to solve it by having a > spice-common.o and link all spice modules to it, to share code? > > Fam >