From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752966AbbE0QZN (ORCPT ); Wed, 27 May 2015 12:25:13 -0400 Received: from smtp02.citrix.com ([66.165.176.63]:55981 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752855AbbE0QZM (ORCPT ); Wed, 27 May 2015 12:25:12 -0400 X-IronPort-AV: E=Sophos;i="5.13,506,1427760000"; d="scan'208";a="269069509" Message-ID: <5565EFE2.7050308@citrix.com> Date: Wed, 27 May 2015 17:25:06 +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: 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> In-Reply-To: <1429507420-18201-15-git-send-email-jgross@suse.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 8bit X-DLP: MIA2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. David