From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37761) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VW5z4-0005YK-Jo for qemu-devel@nongnu.org; Tue, 15 Oct 2013 10:52:36 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VW5yy-0000YM-Fa for qemu-devel@nongnu.org; Tue, 15 Oct 2013 10:52:30 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59849) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VW5yy-0000YA-5M for qemu-devel@nongnu.org; Tue, 15 Oct 2013 10:52:24 -0400 Date: Tue, 15 Oct 2013 17:54:50 +0300 From: "Michael S. Tsirkin" Message-ID: <20131015145450.GA7897@redhat.com> References: <1381762577-12526-1-git-send-email-mst@redhat.com> <1381762577-12526-43-git-send-email-mst@redhat.com> <525D51C3.2050201@redhat.com> <20131015143530.GA7763@redhat.com> <525D5630.1030801@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <525D5630.1030801@redhat.com> Subject: Re: [Qemu-devel] [PULL 42/43] piix4: add acpi pci hotplug support List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: peter.maydell@linaro.org, marcel.a@redhat.com, qemu-devel@nongnu.org, kraxel@redhat.com, Anthony Liguori , imammedo@redhat.com On Tue, Oct 15, 2013 at 04:50:24PM +0200, Paolo Bonzini wrote: > Il 15/10/2013 16:35, Michael S. Tsirkin ha scritto: > > On Tue, Oct 15, 2013 at 04:31:31PM +0200, Paolo Bonzini wrote: > >> Il 14/10/2013 17:01, Michael S. Tsirkin ha scritto: > >>> - VMSTATE_STRUCT(pci0_status, PIIX4PMState, 2, vmstate_pci_status, > >>> - struct pci_status), > >>> + VMSTATE_STRUCT_TEST(pci0_status, PIIX4PMState, > >>> + vmstate_test_no_use_acpi_pci_hotplug, > >>> + 2, vmstate_pci_status, > >>> + struct pci_status), > >> > >> There's no reason to remove this from the stream when a new machine type > >> is in use. You'll just send out zeroes. > > > > Seemed cleaner not to. > > It certainly would be if we had a self-descriptive migration stream format. > > However, what we have is "send bytes, parse them on the destination, > hope the format matches". Hence, anything that makes the format less > declarative adds to the complication and complicates debugging. This is > the same reason why I prefer a subsection for the new hotplug stuff---it > makes the format more declarative and self-descriptive. > > Paolo I understand for the subsection but why is removing useless bytes from there making it less descriptive? > >>> + VMSTATE_PCI_HOTPLUG(acpi_pci_hotplug, PIIX4PMState, > >>> + vmstate_test_use_acpi_pci_hotplug), > >> > >> This works, but it is a bit different from other cases that are already > >> present, which use a subsection. It is a bit ugly because it looks like > >> a version-1 field, but in fact it is not version 1. > >> > >> I'll let other people decide whether it's acceptable or not, but I'm > >> leaning towards asking you to use a subsection. > >> > >> Paolo