From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753630AbbE0RKY (ORCPT ); Wed, 27 May 2015 13:10:24 -0400 Received: from smtp.citrix.com ([66.165.176.89]:62629 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753610AbbE0RKT (ORCPT ); Wed, 27 May 2015 13:10:19 -0400 X-IronPort-AV: E=Sophos;i="5.13,506,1427760000"; d="scan'208";a="266478234" Message-ID: <5565F977.102@citrix.com> Date: Wed, 27 May 2015 18:05:59 +0100 From: David Vrabel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.4.0 MIME-Version: 1.0 To: David Vrabel , Juergen Gross , , , , Subject: Re: [Xen-devel] [Patch V3 14/15] xen: allow more than 512 GB of RAM for 64 bit pv-domains References: <1429507420-18201-1-git-send-email-jgross@suse.com> <1429507420-18201-15-git-send-email-jgross@suse.com> <5565EFE2.7050308@citrix.com> In-Reply-To: <5565EFE2.7050308@citrix.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-DLP: MIA2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 27/05/15 17:25, David Vrabel wrote: > On 20/04/15 06:23, Juergen Gross wrote: >> 64 bit pv-domains under Xen are limited to 512 GB of RAM today. The >> main reason has been the 3 level p2m tree, which was replaced by the >> virtual mapped linear p2m list. Parallel to the p2m list which is >> being used by the kernel itself there is a 3 level mfn tree for usage >> by the Xen tools and eventually for crash dump analysis. For this tree >> the linear p2m list can serve as a replacement, too. As the kernel >> can't know whether the tools are capable of dealing with the p2m list >> instead of the mfn tree, the limit of 512 GB can't be dropped in all >> cases. >> >> This patch replaces the hard limit by a kernel parameter which tells >> the kernel to obey the 512 GB limit or not. The default is selected by >> a configuration parameter which specifies whether the 512 GB limit >> should be active per default for domUs (domain save/restore/migration >> and crash dump analysis are affected). >> >> Memory above the domain limit is returned to the hypervisor instead of >> being identity mapped, which was wrong anyway. >> >> The kernel configuration parameter to specify the maximum size of a >> domain can be deleted, as it is not relevant any more. > > Something in this patch breaks the hvc console in my test domU. > > kernel BUG at /local/davidvr/work/k.org/tip/drivers/tty/hvc/hvc_xen.c:153 > > Which suggests the hvc driver mapped the wrong console ring frame. Sorry, it's patch #13 (xen: move p2m list if conflicting with e820 map) that seems to be bad. David