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dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:60022 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kfQ4L-0001wH-Ou for qemu-devel@archiver.kernel.org; Wed, 18 Nov 2020 11:12:29 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:48662) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kfQ3T-0000yF-LC for qemu-devel@nongnu.org; Wed, 18 Nov 2020 11:11:35 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:39629) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kfQ3Q-00018H-LL for qemu-devel@nongnu.org; Wed, 18 Nov 2020 11:11:35 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1605715891; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=WX3aC0ZUypKugpxfHUenvZnCL3jpfxuBwA3kKgiGuCs=; b=X1b1TmpcoQcuBBa2iBubYM77wfeH5p+60URq71dWRXIYYmrEM/3P99BZ2hJphvUyPbmqZt zSVkkakpGMA2hIZUxl++EygcCQ8eDNytL4cIPNRPepIkFM8pXVgpPWgxE/yJSocJBsYpX3 C/yG9SL256k/SP87VDXX33olgCaT/ZY= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-579-7NaURj9KMQGGIqzgL3XMZg-1; Wed, 18 Nov 2020 11:11:30 -0500 X-MC-Unique: 7NaURj9KMQGGIqzgL3XMZg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 5A209D8EC4; Wed, 18 Nov 2020 16:11:27 +0000 (UTC) Received: from localhost (ovpn-115-101.rdu2.redhat.com [10.10.115.101]) by smtp.corp.redhat.com (Postfix) with ESMTP id 000F35D6A8; Wed, 18 Nov 2020 16:11:20 +0000 (UTC) Date: Wed, 18 Nov 2020 11:11:19 -0500 From: Eduardo Habkost To: Paolo Bonzini Subject: Re: [RFC v3 8/9] module: introduce MODULE_INIT_ACCEL_CPU Message-ID: <20201118161119.GJ1509407@habkost.net> References: <20201118102936.25569-1-cfontana@suse.de> <20201118102936.25569-9-cfontana@suse.de> <20201118124845.GC1509407@habkost.net> <6093de34-807d-3840-5402-4769385dd894@suse.de> <8f829e99-c346-00bc-efdd-3e6d69cfba35@redhat.com> <20201118143643.GF1509407@habkost.net> <20201118152552.GG1509407@habkost.net> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=ehabkost@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=ehabkost@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/11/18 00:38:29 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Laurent Vivier , Bruce Rogers , Thomas Huth , Stefano Stabellini , Paul Durrant , Olaf Hering , Jason Wang , Marcelo Tosatti , qemu-devel@nongnu.org, Peter Xu , Dario Faggioli , Roman Bolshakov , Cameron Esfahani , Colin Xu , Wenchao Wang , Anthony Perard , haxm-team@intel.com, Sunil Muthuswamy , Richard Henderson , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Claudio Fontana Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Nov 18, 2020 at 04:43:19PM +0100, Paolo Bonzini wrote: > Il mer 18 nov 2020, 16:26 Eduardo Habkost ha scritto: > > > > > > The alternative is to store the (type, function) tuple directly, with the > > > type as a string. Then you can just use type_init. > > > > Right. Let's build on top of that: > > > > Another alternative would be to store a (type, X86CPUAccel) tuple > > directly, with the type as string. This would save the extra > > indirection of the x86_cpu_accel_init() call. > > > > It turns out we already have a mechanism to register and store > > (type, StructContainingFunctionPointers) tuples at initialization > > time: QOM. > > > > X86CPUAccel can become X86CPUAccelClass, and be registered as a > > QOM type. It could be a subtype of TYPE_ACCEL or not, it > > shouldn't matter. > > > > It would be a weird type that isn't instantiated, and/or that does nothing > but monkey patching other classes. I don't think it's a good fit. The whole point of this would be to avoid monkey patching other classes. Why wouldn't we instantiate it? There's a huge number of static variables in target/i386/kvm.c that could be moved to that object. Sounds like a perfect fit for me. I won't try to stop you if you really want to invent a brand new (name => CollectionOfFunctionPointers) registry, but it seems unnecessary. > > Yet another possibility is to use GHashTable. It is limited to one value > per key, but it's enough if everything is kept local to {hw,target}/i386. > If needed a new function pointer can be added to MachineClass, implemented > in X86MachineState (where the GHashTable would also be) and called in > accel.c. > > Paolo > > Paolo > > > > I remember this was suggested in a previous thread, but I don't > > remember if there were any objections. > > > > > > > > > Making sure module_call_init() is called at the correct moment is > > > > not easier or safer than just making sure accel_init_machine() > > > > (or another init function you create) is called at the correct > > > > moment. > > > > > > Since there is a way to do it without a new level, that would of course > > be > > > fine for me too. Let me explain however why I think Claudio's design had > > > module_call_init() misplaced and what the fundamental difference is. The > > > basic phases in qemu_init() are: > > > > > > - initialize stuff > > > - parse command line > > > - create machine > > > - create accelerator > > > - initialize machine > > > - create devices > > > - start > > > > > > with a mess of other object creation sprinkled between the various phases > > > (but we don't care about those). > > > > > > What I object to, is calling module_call_init() after the "initialize > > stuff" > > > phase. Claudio was using it to call the function directly, so it had to > > be > > > exactly at "create accelerator". This is different from all other > > > module_call_init() calls, which are done very early. > > > > I agree. > > > > > > > > With the implementation I sketched, accel_register_call must still be > > done > > > after type_init, so there's still an ordering constraint, but all it's > > doing > > > is registering a callback in the "initialize stuff" phase. > > > > Makes sense, if we really want to introduce a new accel_register_call() > > abstraction. I don't think we need it, though. > > > > -- > > Eduardo > > > > -- Eduardo