From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760249Ab0HEOPK (ORCPT ); Thu, 5 Aug 2010 10:15:10 -0400 Received: from terminus.zytor.com ([198.137.202.10]:59928 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759160Ab0HEOPG (ORCPT ); Thu, 5 Aug 2010 10:15:06 -0400 Message-ID: <4C5AC736.20903@zytor.com> Date: Thu, 05 Aug 2010 07:14:14 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.7) Gecko/20100720 Fedora/3.1.1-1.fc13 Thunderbird/3.1.1 MIME-Version: 1.0 To: "Roedel, Joerg" CC: Borislav Petkov , "mingo@elte.hu" , "tglx@linutronix.de" , "Herrmann3, Andreas" , "Seidel, Conny" , "Sarathy, Bhavna" , "greg@kroah.com" , "x86@kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 1/2] x86-32: Fix crashes with CPU hotplug on AMD machines References: <1280940316-7966-1-git-send-email-bp@amd64.org> <1280940316-7966-2-git-send-email-bp@amd64.org> <4C59F24B.1010702@zytor.com> <20100805074503.GI18307@amd.com> In-Reply-To: <20100805074503.GI18307@amd.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/05/2010 12:45 AM, Roedel, Joerg wrote: > > To make sure I understand correctly, you suggest to initialize > tramponline_pg_dir in the boot sequence of the first cpu and fork > swapper_pg_dir from it later on? > Correct. >> I realize this isn't how the 64-bit code works at the moment, but in a >> lot of ways I think it would be better if it did. > > Yeah, may make sense. This patch already brings the 32 bit > implementation closer to the 64 bit one. On 64 bit things are somewhat > simpler because the tramponline page table can be defined at > compile-time there (contains only 2 pgd_t entries) while on 32 bit we > have to initialize it at runtime. Correct, again. It's unclear to me if we can get away with the very simple 64-bit approach -- in particular, not including all the 1:1 mappings in the kernel -- for all future users, though. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.