From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52544) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WzJQQ-0002pU-KI for qemu-devel@nongnu.org; Tue, 24 Jun 2014 01:37:54 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WzJQJ-0006dP-18 for qemu-devel@nongnu.org; Tue, 24 Jun 2014 01:37:46 -0400 Received: from mail-pd0-f179.google.com ([209.85.192.179]:60433) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WzJQI-0006dD-RC for qemu-devel@nongnu.org; Tue, 24 Jun 2014 01:37:38 -0400 Received: by mail-pd0-f179.google.com with SMTP id w10so6526226pde.24 for ; Mon, 23 Jun 2014 22:37:37 -0700 (PDT) Message-ID: <53A90E9C.2020300@ozlabs.ru> Date: Tue, 24 Jun 2014 15:37:32 +1000 From: Alexey Kardashevskiy MIME-Version: 1.0 References: <53A8366B.1020301@ozlabs.ru> <53A840C8.8060607@redhat.com> <53A89D98.3030708@ozlabs.ru> <53A9095B.3070803@redhat.com> In-Reply-To: <53A9095B.3070803@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] machines and versions - why so many? List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini , "qemu-devel@nongnu.org" Cc: Paul Mackerras , =?UTF-8?B?QW5kcmVhcyBGw6RyYmVy?= , Alexander Graf On 06/24/2014 03:15 PM, Paolo Bonzini wrote: > Il 23/06/2014 23:35, Alexey Kardashevskiy ha scritto: >> nec-usb-xhci is off for PC_COMPAT_1_3 because of what? PIIX emulation was >> broken in 1.3? Or nec-usb-xhci? > > nec-usb-xhci is not "off". Yes, my bad, I understood (but explained this wrong) that XHCI is enabled but without MSI. > > .driver = "nec-usb-xhci",\ > .property = "msi",\ > .value = "off",\ > > What's off is MSI (and MSI-X), because it wasn't implemented. > >> If it is the latter, why is the tweak limited by PC? > > Because at the time nobody cared about migration compatibility (even now > only pSeries is starting to care). "only pSeries"? There are plenty of x86 machines already and if it is not for migration support, then what are they all for? :) >> Looks like I must copy PC_COMPAT_X_X as PSERIES_COMPAT_X_X starting 1.6 (or >> 1.7 - whichever starts supporting migration well enough on pseries) because >> pretty much of what they do is tweaking PCI devices and we can have all of >> these devices on pseries. > > It's not necessary to do this retroactively, unless you're planning to test > forward migration from 1.6 to 2.1. Just start with 2.2 (and add > pseries-2.1 now as an alias). > > Note that firmware interfaces and CPU features should also be versioned if > they're guest visible. That's the point of functions like pc_compat_1_6. > >> And then keep an eye on what is happening in PC >> world to copy same tweaks to pseries as they come. Is that correct? > > Yes. We should come up sooner or later with a way to share the tweaks though. > >> Others (ARM, s390) do not do that because they do not support PCI? Or >> migration? Or some other reason? > > This is not limited to PCI. Others do not support migration across > different QEMU versions. Yeah, I got that now. Thanks! -- Alexey