From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48272) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fFyKr-0006gA-2l for qemu-devel@nongnu.org; Tue, 08 May 2018 04:51:07 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fFyKn-0004eV-Vh for qemu-devel@nongnu.org; Tue, 08 May 2018 04:51:01 -0400 Received: from indium.canonical.com ([91.189.90.7]:41340) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1fFyKn-0004dt-MH for qemu-devel@nongnu.org; Tue, 08 May 2018 04:50:57 -0400 Received: from loganberry.canonical.com ([91.189.90.37]) by indium.canonical.com with esmtp (Exim 4.86_2 #2 (Debian)) id 1fFyKk-0006rI-I2 for ; Tue, 08 May 2018 08:50:54 +0000 Received: from loganberry.canonical.com (localhost [127.0.0.1]) by loganberry.canonical.com (Postfix) with ESMTP id 45B092E81C3 for ; Tue, 8 May 2018 08:50:50 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Date: Tue, 08 May 2018 08:37:22 -0000 From: "Dr. David Alan Gilbert" Reply-To: Bug 1769053 <1769053@bugs.launchpad.net> Sender: bounces@canonical.com References: <152541524728.557.4600864098110042577.malonedeb@gac.canonical.com> <152568921469.6485.15990399219355923244.malone@chaenomeles.canonical.com> Message-Id: <20180508083722.GB2500@work-vm> Errors-To: bounces@canonical.com Subject: Re: [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 * ChristianEhrhardt (1769053@bugs.launchpad.net) wrote: > > 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. I assume so, but I've not looked at the detail of that. > > 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 successf= ully 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) = works just fine as expected. Here ~1063 GB from /proc/meminfo > MemTotal: 1114676492 kB OK, good - that suggests there's nothing missing. We enable host-phys-bits=3Dtrue by default I think (in our machine type?) > 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. The problem is there are a whole bunch of things that are hard to deal with: a) Cheaper CPUs tend to have smaller phys-bits even in the same generation; e.g. my laptop is still 36 bits, a lot are 39 bits. I think the same is true of the Xeon E3-.... family. It makes it hard to know what to pick when you're going to allow migration. b) Reasoning about the total address size range is difficult; you've got to take into account PCI address space and hot plug space etc to know where the upper edge is. Dave > 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 subscribed to the bug > report. > 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/= mapper/ubuntu--vg-root ro quiet splash transparent_hugepage=3Dmadvise vt.ha= ndoff=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.:pnXPS13= 9360: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 -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK -- = 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