From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55674) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VUFD4-0008Vp-VW for qemu-devel@nongnu.org; Thu, 10 Oct 2013 08:19:24 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VUFCu-0004Fu-7V for qemu-devel@nongnu.org; Thu, 10 Oct 2013 08:19:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52057) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VUFCt-0004Fe-Vc for qemu-devel@nongnu.org; Thu, 10 Oct 2013 08:19:08 -0400 Date: Thu, 10 Oct 2013 15:21:32 +0300 From: "Michael S. Tsirkin" Message-ID: <20131010122132.GA7884@redhat.com> References: <1381321384-17270-1-git-send-email-imammedo@redhat.com> <1381324328.12583.102.camel@nilsson.home.kraxel.org> <20131009192734.67770b73@thinkpad> <1381402583.15451.70.camel@nilsson.home.kraxel.org> <20131010113541.GD7582@redhat.com> <1381407256.15451.86.camel@nilsson.home.kraxel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1381407256.15451.86.camel@nilsson.home.kraxel.org> Subject: Re: [Qemu-devel] [RFC] map 64-bit PCI devices after all possible RAM List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gerd Hoffmann Cc: Igor Mammedov , kevin@koconnor.net, seabios@seabios.org, qemu-devel@nongnu.org, pbonzini@redhat.com On Thu, Oct 10, 2013 at 02:14:16PM +0200, Gerd Hoffmann wrote: > Hi, > > > I think the simplest way to do all this is simply to tell seabios > > that we have more memory. seabios already programs 64 bit BARs > > higher than memory. > > Hmm? As I understand Igor just wants some address space for memory > hotplug. So there wouldn't be memory there (yet). And telling seabios > there is although there isn't will make seabios place wrong info into > the e820 tables. Not going to fly. True. Maybe we should get some smbios stuff from qemu too. > > I think the issue is with legacy guests. > > E.g. if VCPU claims to support 50 bit of memory > > do we put high PCI memory at 1 << 50? > > If yes old guests which expect at most 40 bit > > will not be able to use it. > > Hmm. Sure such guests exist? I wouldn't be surprised. At least some windows guests crash if you try to tell them your system has too much physical memory (e.g. 2^48). > Note this is physical address lines, not > virtual address space (where you might need an additional level of > pagetables to fully use it, which is not something we could expect old > guests being able to handle). > > cheers, > Gerd >