From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59404) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YaJYr-0005DO-Iv for qemu-devel@nongnu.org; Tue, 24 Mar 2015 03:47:42 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YaJYm-0002ff-Iq for qemu-devel@nongnu.org; Tue, 24 Mar 2015 03:47:41 -0400 Received: from mail-wi0-x22d.google.com ([2a00:1450:400c:c05::22d]:35831) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YaJYm-0002fZ-Br for qemu-devel@nongnu.org; Tue, 24 Mar 2015 03:47:36 -0400 Received: by wibdy8 with SMTP id dy8so67483153wib.0 for ; Tue, 24 Mar 2015 00:47:35 -0700 (PDT) Sender: Paolo Bonzini Message-ID: <55111692.1080705@redhat.com> Date: Tue, 24 Mar 2015 08:47:30 +0100 From: Paolo Bonzini MIME-Version: 1.0 References: <1427130328-3629-1-git-send-email-pbonzini@redhat.com> <55105971.3000708@redhat.com> <551059A0.9060602@suse.de> <5510736B.8000107@redhat.com> <55108CF2.7010508@redhat.com> In-Reply-To: <55108CF2.7010508@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH for-2.3] powerpc: fix -machine usb=no for newworld and pseries machines List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Marcel Apfelbaum , Alexander Graf , qemu-devel@nongnu.org Cc: marcel.a@redhat.com On 23/03/2015 23:00, Marcel Apfelbaum wrote: >>>> I know it comes to solve a bug, but we talked about it in another mail >>>> thread and this change in semantics was approved. I forgot to reply to this---my understanding is that it was okay for the sake of your patch series, but it would be fixed before 2.3. >>>> Let me explain *why* I don't like it. >>>> 1. We add an "usb_disabled" field to a base class (actually object) >>>> of all the machines and the only place it is interesting is >>>> for 2 machines on ppc. >> >> So we do for kernel_irqchip_requested/allowed. Both approaches could be >> replaced by a tri-state on/off/auto. > Personally I prefer this one, but out of the scope of this patch. Yes, that was my rationale as well. >>>> 2. Even for these 2 machines, the scenario of defaults=on and usb=off >>>> is not practical. >> >> Why? For example you could add a virtio-input device instead of a USB >> keyboard and mouse. > You got me there :) > From what I understood for those boards there is no need for this > combination but I don't know them enough (OK.. at all). Well, you can always find a reason. USB is a good default, but it doesn't have to be the only one. You might even be okay with USB, but prefer a different host controller. > Bottom line, of course I don't have anything against fixing this bug, > my problem was only with the way we add those fields (usb_disabled), > maybe a three state QOM property (and variable behind it) is a > solution, but not for now of course. I think the QOM property should not be tristate, only the variable. Another possibility is backing "xyz" with a bool xyz, but adding a bool xyz_set. Then irqchip_required = irqchip_set && irqchip, and irqchip_allowed = !irqchip_set || irqchip. Paolo > I also didn't like the required/allowed fields and I added them anyway... > > Thanks, > Marcel > > >> >> Paolo >> > > >