From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51932) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1azktK-0001dE-AK for qemu-devel@nongnu.org; Mon, 09 May 2016 09:06:34 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1azktE-00005B-VP for qemu-devel@nongnu.org; Mon, 09 May 2016 09:06:30 -0400 Received: from e06smtp07.uk.ibm.com ([195.75.94.103]:55790) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1azktE-000054-J0 for qemu-devel@nongnu.org; Mon, 09 May 2016 09:06:24 -0400 Received: from localhost by e06smtp07.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 9 May 2016 14:06:22 +0100 Received: from b06cxnps3074.portsmouth.uk.ibm.com (d06relay09.portsmouth.uk.ibm.com [9.149.109.194]) by d06dlp01.portsmouth.uk.ibm.com (Postfix) with ESMTP id 42F3E17D8042 for ; Mon, 9 May 2016 14:07:17 +0100 (BST) Received: from d06av01.portsmouth.uk.ibm.com (d06av01.portsmouth.uk.ibm.com [9.149.37.212]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u49D6KDd8061278 for ; Mon, 9 May 2016 13:06:20 GMT Received: from d06av01.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av01.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u49D6KlU006750 for ; Mon, 9 May 2016 07:06:20 -0600 Date: Mon, 9 May 2016 15:06:18 +0200 From: David Hildenbrand Message-ID: <20160509150618.0a9fe227@thinkpad-w530> In-Reply-To: <20160509123630.GS4457@thinpad.lan.raisama.net> References: <1462558292-2126-1-git-send-email-ehabkost@redhat.com> <1462558292-2126-8-git-send-email-ehabkost@redhat.com> <20160509105453.57b54a89@thinkpad-w530> <20160509120041.GR4457@thinpad.lan.raisama.net> <20160509140505.701b9dd5@thinkpad-w530> <20160509123630.GS4457@thinpad.lan.raisama.net> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 7/9] qmp: Add runnability information to query-cpu-definitions List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eduardo Habkost Cc: qemu-devel@nongnu.org, Jiri Denemark , Andreas =?UTF-8?B?RsOkcmJlcg==?= , Igor Mammedov , libvir-list@redhat.com, Michael Mueller , Christian Borntraeger , Cornelia Huck , Markus Armbruster > > > > > > > > Just FYI, on other architectures (e.g. s390x), other conditions (e.g. cpu > > > > generation) also define if a CPU model is runnable, so the pure availability of > > > > features does not mean that a cpu model is runnable. > > > > > > > > We could have runnable=false and unavailable-features being an empty list. > > > > > > Even on those cases, can't the root cause be mapped to a QOM > > > property name (e.g. "cpu-generation"), even if it's property that > > > can't be changed by the user? > > > > In the current state, no. > > But it could be implemented by s390x in the future, if it's > considered useful, right? Yes, we could fit that into read-only properties if we would ever need it (like cpu-generation you mentioned and cpu-ga-level - both will always be read-only). However we could come up with more optional fields for that in the future. (like unsupported-values or sth. like that). I actually prefer unavailable-features over runnability-blockers. > > > > > So I think for runnable=false: > > a) unavailable-features set -> can be made runnable > > b) unavailable-features not set -> cannot be made runnable > > > > would be enough. > > I understand it would be enough, but I would like to at least > define semantics that would make sense for all architectures in > case it gets implemented in the future. Would the proposal below > make sense? > Yes, I think so. However to really make good hints, upper layers would most likely need more information about the exact problem with a property - maybe something like an enum value per problematic property. (UNAVAILABLE_FEATURE, VALUE_TOO_BIG, VALUE_TOO_SMALL, UNSUPPORTED_VALUE) ... > > > > > > We could replace this with something more generic, like: > > > > > > @runnability-blockers: List of attributes that prevent the CPU > > > model from running in the current host. > > > > > > A list of QOM property names that represent CPU model > > > attributes that prevent the CPU from running. If the QOM > > > property is read-only, that means the CPU model can never run > > > in the current host. If the property is read-write, it means > > > that it MAY be possible to run the CPU model in the current > > > host if that property is changed. > > > > > > Management software can use it as hints to suggest or choose an > > > alternative for the user, or just to generate meaningful error > > > messages explaining why the CPU model can't be used. > > > > > > (I am looking for a better name than "runnability-blockers"). > > > Not sure which approach would be better. David