From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 1/2] kvm tools: Add memory gap for larger RAM sizes Date: Wed, 11 May 2011 12:06:00 +0300 Message-ID: <4DCA5178.9030402@redhat.com> References: <1305061513-28360-1-git-send-email-levinsasha928@gmail.com> <4DCA4917.9020802@redhat.com> <20110511084402.GB7112@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Pekka Enberg , Sasha Levin , asias.hejun@gmail.com, prasadjoshi124@gmail.com, gorcunov@gmail.com, kvm@vger.kernel.org To: Ingo Molnar Return-path: Received: from mx1.redhat.com ([209.132.183.28]:35488 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757054Ab1EKQR1 (ORCPT ); Wed, 11 May 2011 12:17:27 -0400 In-Reply-To: <20110511084402.GB7112@elte.hu> Sender: kvm-owner@vger.kernel.org List-ID: On 05/11/2011 11:44 AM, Ingo Molnar wrote: > > > > It doesn't work in general - if you have a PCI device with a BAR > > (like a video card framebuffer), then you need allocations for main > > memory (0+) and pci (0xe000000+). You can't have a contiguous > > mapping on i386 containing both. > > I think in tools/kvm/ we can ignore i386 hosts that would like to map more RAM > than they have virtual address space for ... > > Guests up to 1-2 gigs of RAM will still work fine. > It doesn't work. Consider a guest with 128MB of RAM mapped at 0-128MB and an 8MB framebuffer mapped at 0xe0000000. There's no way to present this in a contiguous space. Well, I guess you can map the framebuffer lower, but that means giving up memory hotplug if you ever wish to implement it (and doesn't allow the guest to remap the framebuffer if it wishes to). -- error compiling committee.c: too many arguments to function