From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50248) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VdXoz-00018l-CC for qemu-devel@nongnu.org; Mon, 04 Nov 2013 23:00:54 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VdXov-0006gv-U8 for qemu-devel@nongnu.org; Mon, 04 Nov 2013 23:00:53 -0500 Date: Tue, 5 Nov 2013 15:00:10 +1100 From: Paul Mackerras Message-ID: <20131105040010.GB2832@drongo> References: <1383536166-8673-1-git-send-email-aik@ozlabs.ru> <527761B7.8050402@ozlabs.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [PATCH] RFC: powerpc: add PVR compatibility check List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alexander Graf Cc: Alexey Kardashevskiy , QEMU Developers , "list@suse.de:PReP" , Anthony Liguori , open@suse.de, Andreas =?iso-8859-1?Q?F=E4rber?= On Mon, Nov 04, 2013 at 10:05:58AM +0100, Alexander Graf wrote: > > Yeah, we really need to check that guest vpcu == host vcpu for HV KVM. In general I agree, but the one difficulty I see is that a check for exact equality will interact badly with qemu's habit of picking a specific processor version when the user specifies something general like "POWER7". So if the user does -cpu POWER7 on a machine with (for example) a POWER7 v2.1 processor, but qemu arbitrarily picks the PVR for POWER7 v2.3, then it will fail, which will be completely puzzling to the user -- "I asked for POWER7, and it is a POWER7, what's the problem??". Maybe if the user asks for a non-specific processor type, and the host's PVR matches the request, then qemu should take the host's PVR rather than just picking some arbitrary processor version. Paul.