From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53446) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fFdZn-0005Al-QJ for qemu-devel@nongnu.org; Mon, 07 May 2018 06:41:05 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fFdZk-0007Te-JT for qemu-devel@nongnu.org; Mon, 07 May 2018 06:41:03 -0400 Received: from indium.canonical.com ([91.189.90.7]:38300) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1fFdZk-0007SP-DB for qemu-devel@nongnu.org; Mon, 07 May 2018 06:41:00 -0400 Received: from loganberry.canonical.com ([91.189.90.37]) by indium.canonical.com with esmtp (Exim 4.86_2 #2 (Debian)) id 1fFdZi-0005IK-M8 for ; Mon, 07 May 2018 10:40:58 +0000 Received: from loganberry.canonical.com (localhost [127.0.0.1]) by loganberry.canonical.com (Postfix) with ESMTP id A54D82E80D2 for ; Mon, 7 May 2018 10:40:58 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Date: Mon, 07 May 2018 10:33:34 -0000 From: ChristianEhrhardt <1769053@bugs.launchpad.net> Reply-To: Bug 1769053 <1769053@bugs.launchpad.net> Sender: bounces@canonical.com References: <152541524728.557.4600864098110042577.malonedeb@gac.canonical.com> Message-Id: <152568921469.6485.15990399219355923244.malone@chaenomeles.canonical.com> Errors-To: bounces@canonical.com Subject: [Qemu-devel] [Bug 1769053] Re: Cannot start a guest with more than 1TB of RAM List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org > Interesting; I thought this was supposed to work. Exactly that was my thought when triaging it initially Furthermore I assume people working la57 (https://lwn.net/Articles/730925/)= and such ran tests on much bigger sizes. > Ah right Dan, if you're seeing the 40 bits physical in the guest you definitely need to try the flags I suggest in comment 6; host-phys- bits=3Dtrue should work for you. I tested Bionic to be at least on libvirt 4.0 / qemu 2.11.1 when we want to check things under the "supposed to work now" flag. Defaults: Host: address sizes : 46 bits physical, 48 bits virtual Guest: address sizes : 40 bits physical, 48 bits virtual I ensured that with option -cpu host,host-phys-bits=3Dtrue set I successful= ly get what my host can provide in the guest: Guest: address sizes : 46 bits physical, 48 bits virtual Starting a guest with that >1TB (that would be mostly on swap if needed) wo= rks just fine as expected. Here ~1063 GB from /proc/meminfo MemTotal: 1114676492 kB I also checked a more compatible approach like -cpu qemu64,phys-bits=3D42 and that works as well. IMHO - if anything - one could argue that libvirt/qemu could be smarter about e.g. auto adding those arguments (or print a warning) when crossing a certain memory size. So for now I'd stick to the "actually works" summary and keep the status to incomplete. -- = You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1769053 Title: Cannot start a guest with more than 1TB of RAM Status in QEMU: Incomplete Status in qemu package in Ubuntu: Incomplete Bug description: Attempting to start a KVM guest with more than 1TB of RAM fails. It looks like we might need some extra patches: https://lists.gnu.org/archive/html/qemu-discuss/2017-12/msg00005.html ProblemType: Bug DistroRelease: Ubuntu 18.04 Package: qemu-system-x86 1:2.11+dfsg-1ubuntu7 ProcVersionSignature: Ubuntu 4.15.0-20.21-generic 4.15.17 Uname: Linux 4.15.0-20-generic x86_64 ApportVersion: 2.20.9-0ubuntu7 Architecture: amd64 CurrentDesktop: Unity:Unity7:ubuntu Date: Fri May 4 16:21:14 2018 InstallationDate: Installed on 2017-04-05 (393 days ago) InstallationMedia: Ubuntu 16.10 "Yakkety Yak" - Release amd64 (20161012.2) MachineType: Dell Inc. XPS 13 9360 ProcKernelCmdLine: BOOT_IMAGE=3D/vmlinuz-4.15.0-20-generic root=3D/dev/ma= pper/ubuntu--vg-root ro quiet splash transparent_hugepage=3Dmadvise vt.hand= off=3D1 SourcePackage: qemu UpgradeStatus: Upgraded to bionic on 2018-04-30 (3 days ago) dmi.bios.date: 02/26/2018 dmi.bios.vendor: Dell Inc. dmi.bios.version: 2.6.2 dmi.board.name: 0PF86Y dmi.board.vendor: Dell Inc. dmi.board.version: A00 dmi.chassis.type: 9 dmi.chassis.vendor: Dell Inc. dmi.modalias: dmi:bvnDellInc.:bvr2.6.2:bd02/26/2018:svnDellInc.:pnXPS1393= 60:pvr:rvnDellInc.:rn0PF86Y:rvrA00:cvnDellInc.:ct9:cvr: dmi.product.family: XPS dmi.product.name: XPS 13 9360 dmi.sys.vendor: Dell Inc. To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1769053/+subscriptions