From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48823) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZCj33-0000Fv-Ji for qemu-devel@nongnu.org; Wed, 08 Jul 2015 02:41:39 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZCj2z-0000yX-J6 for qemu-devel@nongnu.org; Wed, 08 Jul 2015 02:41:37 -0400 Received: from mail-pa0-f42.google.com ([209.85.220.42]:34769) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZCj2z-0000yK-EK for qemu-devel@nongnu.org; Wed, 08 Jul 2015 02:41:33 -0400 Received: by pabvl15 with SMTP id vl15so126296947pab.1 for ; Tue, 07 Jul 2015 23:41:33 -0700 (PDT) References: <1425520601-3610-1-git-send-email-aik@ozlabs.ru> <54F85756.6040904@suse.de> <55066306.9060906@ozlabs.ru> <5506B31D.1060504@suse.de> <55075D7E.8060104@ozlabs.ru> <559CC538.8080801@ozlabs.ru> From: Alexey Kardashevskiy Message-ID: <559CC616.2060404@ozlabs.ru> Date: Wed, 8 Jul 2015 16:41:26 +1000 MIME-Version: 1.0 In-Reply-To: <559CC538.8080801@ozlabs.ru> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [RFC PATCH] target-ppc: Register CPU class per family only when needed List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: =?UTF-8?Q?Andreas_F=c3=a4rber?= , Alexander Graf , qemu-devel@nongnu.org Cc: qemu-ppc@nongnu.org, David Gibson On 07/08/2015 04:37 PM, Alexey Kardashevskiy wrote: > Adding David to this old conversation. This is the patch: http://patchwork.ozlabs.org/patch/446544/ > > On 03/17/2015 09:47 AM, Alexey Kardashevskiy wrote: >> On 03/16/2015 09:40 PM, Andreas Färber wrote: >>> Am 16.03.2015 um 05:58 schrieb Alexey Kardashevskiy: >>>> On 03/06/2015 12:17 AM, Alexander Graf wrote: >>>>> On 05.03.15 02:56, Alexey Kardashevskiy wrote: >>>>>> At the moment when running in KVM mode, QEMU registers "host" class to >>>>>> match the current CPU PVR value. It also registers another CPU class >>>>>> with a CPU family name os if we run QEMU on POWER7 machine, "host" and >>>>>> "POWER7" classes are created, this way we can always use "-cpu POWER7" >>>>>> on the actual POWER7 machine. >>>>>> >>>>>> The existing code uses DeviceClass::desc field of the CPU class as >>>>>> a source for the class name; it was pointed out that it is wrong to use >>>>>> user-visible string as a type name. >>>>>> >>>>>> This adds a common CPU class name into PowerPCCPUClass struct. >>>>>> This makes registration of a CPU named after the family conditional - >>>>>> PowerPCCPUClass::common_cpu_name has to be non-zero. Only POWER7/POWER8 >>>>>> families have this field initialized by now. >>>>>> >>>>>> Signed-off-by: Alexey Kardashevskiy >>>>> >>>>> LGTM. Andreas, do you agree? >>>> >>>> >>>> Ping? >>> >>> No, I don't agree. Inventing a new class field just to distinguish >>> POWER7/POWER8 here seems like a weird idea, >> >> As weird as PVR itself :) >> >>> and the code placement is not fixed either. >> >> What is wrong with the code placement? >> >> >>> I gathered that you want -cpu POWER7 and -cpu POWER8 to work on POWER8 >>> hardware and -cpu POWER7 on POWER7, for migration purposes, correct? >>> >>> What exact PVRs have you tested on and why does it not work without >>> those types despite the PVR masking? To investigate I need a test case. >> >> The real host is 003f 0201. -cpu POWER7 will fail without my patches as >> POWER7 is alias of 003f 0203. >> >> Or real host 004b 0201 - -cpu POWER8 will try 004d 0100 and fail. >> >> >>> Is this just a question of the generic family type being abstract and >>> needing an updated PVR value? >> >> May be. That could help too I suppose. >> >>> Which other fields are actually used? >> >> Sorry, used where? :) >> >> >> > > -- Alexey