From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50898) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YXdnO-000680-JR for qemu-devel@nongnu.org; Mon, 16 Mar 2015 18:47:39 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YXdnJ-0005Y5-KB for qemu-devel@nongnu.org; Mon, 16 Mar 2015 18:47:38 -0400 Received: from mail-pa0-f50.google.com ([209.85.220.50]:33785) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YXdnJ-0005Xx-FG for qemu-devel@nongnu.org; Mon, 16 Mar 2015 18:47:33 -0400 Received: by pagr17 with SMTP id r17so77870277pag.0 for ; Mon, 16 Mar 2015 15:47:32 -0700 (PDT) Message-ID: <55075D7E.8060104@ozlabs.ru> Date: Tue, 17 Mar 2015 09:47:26 +1100 From: Alexey Kardashevskiy MIME-Version: 1.0 References: <1425520601-3610-1-git-send-email-aik@ozlabs.ru> <54F85756.6040904@suse.de> <55066306.9060906@ozlabs.ru> <5506B31D.1060504@suse.de> In-Reply-To: <5506B31D.1060504@suse.de> 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?B?QW5kcmVhcyBGw6RyYmVy?= , Alexander Graf , qemu-devel@nongnu.org Cc: qemu-ppc@nongnu.org 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