From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60692) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wxx09-0006TA-Pm for qemu-devel@nongnu.org; Fri, 20 Jun 2014 07:29:06 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Wxx04-0005Nk-Uw for qemu-devel@nongnu.org; Fri, 20 Jun 2014 07:29:01 -0400 Received: from mailapp01.imgtec.com ([195.59.15.196]:16456) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wxx04-0005NX-PA for qemu-devel@nongnu.org; Fri, 20 Jun 2014 07:28:56 -0400 Message-ID: <53A41AF5.8040704@imgtec.com> Date: Fri, 20 Jun 2014 12:28:53 +0100 From: James Hogan MIME-Version: 1.0 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> <20140620111949.GK24904@hall.aurel32.net> In-Reply-To: <20140620111949.GK24904@hall.aurel32.net> Content-Type: text/plain; charset="ISO-8859-15" Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v5 10/12] hw/mips: malta: Add KVM support List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Aurelien Jarno , Paolo Bonzini Cc: Sanjay Lal , Gleb Natapov , qemu-devel@nongnu.org, kvm@vger.kernel.org, Peter Maydell On 20/06/14 12:19, Aurelien Jarno wrote: > 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. FYI Cavium have been working on a para-virtualised machine which they use with their VZ KVM implementation. They're using lkvm, but I expect it will make sense to port that to QEMU too. lkvm patchset (applied): https://www.mail-archive.com/kvm%40vger.kernel.org/msg102792.html linux kernel patchset (merged in v3.16-rc1): https://www.mail-archive.com/kvm%40vger.kernel.org/msg102806.html Cheers James