From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755155Ab2LNAKl (ORCPT ); Thu, 13 Dec 2012 19:10:41 -0500 Received: from terminus.zytor.com ([198.137.202.10]:41057 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753277Ab2LNAKc (ORCPT ); Thu, 13 Dec 2012 19:10:32 -0500 Message-ID: <50CA6E4C.6000305@zytor.com> Date: Thu, 13 Dec 2012 16:09:48 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Andy Lutomirski CC: Stefani Seibold , linux-kernel@vger.kernel.org, x86@kernel.org, tglx@linutronix.de, mingo@redhat.com, ak@linux.intel.com, aarcange@redhat.com, john.stultz@linaro.org Subject: Re: [PATCH] Add VDSO time function support for x86 32-bit kernel References: <1355343572-23074-1-git-send-email-stefani@seibold.net> <50C9148C.4040308@zytor.com> <1355378005.24283.11.camel@wall-e> <1d3061cb-76d0-4e42-9b75-a975b05384ec@email.android.com> <1355379433.24701.1.camel@wall-e> <1355383038.18653.2.camel@wall-e> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/13/2012 11:32 AM, Andy Lutomirski wrote: > > x32's vdso cheats -- x32 code can see high addresses just fine. The > toolchain just makes it difficult. > > Your best bet is probably to just map the vvar page twice -- once at > the same address as native 32-bit mode (but only for compat tasks) > would use and once in the usual fixmap location. You can't use the > fixmap for the compat mapping, though, since it would be a *user* > address. > > For HPET support, you'd have to have special support. I'd say to skip > it for compat mode. > Whatever data you need you can just map it into the vdso range. There really shouldn't be anything special about that at all. The fixmap stuff is an x86-64 legacy that you don't have to worry about, obviously. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.