From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43659) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1e1wXU-0005VG-CN for qemu-devel@nongnu.org; Tue, 10 Oct 2017 11:33:52 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1e1wXQ-00060w-81 for qemu-devel@nongnu.org; Tue, 10 Oct 2017 11:33:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36352) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1e1wXQ-00060V-0n for qemu-devel@nongnu.org; Tue, 10 Oct 2017 11:33:44 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 192E9A1F41 for ; Tue, 10 Oct 2017 15:33:43 +0000 (UTC) Date: Tue, 10 Oct 2017 12:33:35 -0300 From: Eduardo Habkost Message-ID: <20171010153335.GC3246@localhost.localdomain> References: <20171006215244.27104-1-ehabkost@redhat.com> <20171006215244.27104-2-ehabkost@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [PATCH 1/7] qemu-doc: Document minimum kernel version for KVM in x86_64 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: qemu-devel@nongnu.org, "Michael S. Tsirkin" , Igor Mammedov On Mon, Oct 09, 2017 at 03:40:02PM +0200, Paolo Bonzini wrote: > On 06/10/2017 23:52, Eduardo Habkost wrote: > > The default set of KVM CPU features require the host kernel to > > support them. KVM_PV_EOI is the newest one, and was included on > > Linux v3.6 (Linux commit ae7a2a3f). > > > > Running on an old host might break management software > > expectations because the latest machine-type won't be runnable > > while older machine-types might be runnable. Document v3.6 as > > the minimum kernel version for KVM on x86_64. > > > > Signed-off-by: Eduardo Habkost > > --- > > qemu-doc.texi | 9 +++++++++ > > 1 file changed, 9 insertions(+) > > > > diff --git a/qemu-doc.texi b/qemu-doc.texi > > index ecd186a159..be45b6b6f6 100644 > > --- a/qemu-doc.texi > > +++ b/qemu-doc.texi > > @@ -37,6 +37,7 @@ > > * QEMU System emulator for non PC targets:: > > * QEMU Guest Agent:: > > * QEMU User space emulator:: > > +* System requirements:: > > * Implementation notes:: > > * Deprecated features:: > > * License:: > > @@ -2348,6 +2349,14 @@ Act as if the host page size was 'pagesize' bytes > > Run the emulation in single step mode. > > @end table > > > > +@node System requirements > > +@chapter System requirements > > + > > +@section KVM kernel module > > + > > +On x86_64 hosts, the default set of CPU features enabled by the KVM accelerator > > +require the host to be running Linux v3.6 or newer. > > + > > > > @include qemu-tech.texi > > > > > > Maybe we should expand on the consequences of running on older versions? I intentionally tried to not make any commitment to what should happen if running an older kernel. But a quick explanation of what can happen is probably a good idea. I will try to come up with something. -- Eduardo