Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757533Ab1BKQqu (ORCPT ); Fri, 11 Feb 2011 11:46:50 -0500 Received: from out01.mta.xmission.com ([166.70.13.231]:45828 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754346Ab1BKQqt (ORCPT ); Fri, 11 Feb 2011 11:46:49 -0500 From: ebiederm@xmission.com (Eric W. Biederman) To: Jiri Olsa Cc: tglx@linutronix.de, mingo@redhat.com, x86@kernel.org, linux-kernel@vger.kernel.org References: <1297432830-3912-1-git-send-email-jolsa@redhat.com> Date: Fri, 11 Feb 2011 08:46:41 -0800 In-Reply-To: <1297432830-3912-1-git-send-email-jolsa@redhat.com> (Jiri Olsa's message of "Fri, 11 Feb 2011 15:00:30 +0100") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-XM-SPF: eid=;;;mid=;;;hst=in01.mta.xmission.com;;;ip=98.207.157.188;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1+8kVNrCN/FAPL+HvO9Azqk41rfjcyXAO0= X-SA-Exim-Connect-IP: 98.207.157.188 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -3.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa06 1397; Body=1 Fuz1=1 Fuz2=1] * 0.4 UNTRUSTED_Relay Comes from a non-trusted relay X-Spam-DCC: XMission; sa06 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Jiri Olsa X-Spam-Relay-Country: Subject: Re: [PATCH] x86_64: disable identity mappings statically X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Fri, 06 Aug 2010 16:31:04 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 787 Lines: 22 Jiri Olsa writes: > hi, > > while browsing the page table setup code, I noticed the x86_64 head > code might not need the identity mappings at all. > It seems it's ok to switch it off completely from the begining, > unless I'm missing something. Have you tested it? I expect you will find that we need the identity mapping because before we load this page table we are running with virt==phys and we need the identity mapping retained in the new page table so we can get to the instruction after movq %rax, %cr0. Eric -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/