From mboxrd@z Thu Jan 1 00:00:00 1970 From: Aurelien Jarno Subject: Re: [Qemu-devel] [PATCH v5 10/12] hw/mips: malta: Add KVM support Date: Fri, 20 Jun 2014 13:19:49 +0200 Message-ID: <20140620111949.GK24904@hall.aurel32.net> References: <1403043037-1271-1-git-send-email-james.hogan@imgtec.com> <1403043037-1271-11-git-send-email-james.hogan@imgtec.com> <20140619162748.GO7398@ohm.rr44.fr> <577D5B21-4F8B-4A9A-BD25-A76C76987544@kymasys.com> <20140619214733.GJ24904@hall.aurel32.net> <786372578.29668656.1403244425225.JavaMail.zimbra@redhat.com> <20140620091047.GC13901@ohm.rr44.fr> <53A40F26.7040902@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Cc: Sanjay Lal , James Hogan , qemu-devel@nongnu.org, Peter Maydell , kvm@vger.kernel.org, Gleb Natapov To: Paolo Bonzini Return-path: Received: from hall.aurel32.net ([195.154.112.97]:44853 "EHLO hall.aurel32.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966470AbaFTLTy (ORCPT ); Fri, 20 Jun 2014 07:19:54 -0400 Content-Disposition: inline In-Reply-To: <53A40F26.7040902@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Fri, Jun 20, 2014 at 12:38:30PM +0200, Paolo Bonzini wrote: > Il 20/06/2014 11:10, Aurelien Jarno ha scritto: > >> My idea was to add a machines-specific option umkernel=on, and require it > >> in order to run KVM. Later we can add umkernel=on support for TCG as well, > >> while umkernel=off with KVM requires virtualization extensions. > >> > >> The same option can disable pflash boot. > >> > >> What do you think? > > > >For what I understand the current KVM support in MIPS uses trap and > >emulate and thus doesn't need hardware support, just a recent kernel > >with the option enabled. > > Yes, but work to support virtualization extensions is underway. > Patches were posted a few months ago. > > >That's why I do wonder if there is a real point > >in supporting UM kernels in TCG mode. > > Debugging, mainly. It is sometimes useful to compare TCG with KVM > on x86, and I suppose it could be the same on MIPS. Ok, then we can indeed add a umkernel option, which is always enabled with KVM, and which disable the flash (and why not other devices) in that case. At some point it might be a good idea to add a specific machine for emulation/virtualization, like it is done on ARM, which do not have to handle this kind of devices, and which does not have all the current limitations of the Malta board. -- Aurelien Jarno GPG: 4096R/1DDD8C9B aurelien@aurel32.net http://www.aurel32.net