From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753894Ab2LNIfJ (ORCPT ); Fri, 14 Dec 2012 03:35:09 -0500 Received: from mailhub.sw.ru ([195.214.232.25]:40226 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751088Ab2LNIfI (ORCPT ); Fri, 14 Dec 2012 03:35:08 -0500 Message-ID: <50CAE485.5020608@parallels.com> Date: Fri, 14 Dec 2012 12:34:13 +0400 From: Pavel Emelyanov User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120605 Thunderbird/13.0 MIME-Version: 1.0 To: Andy Lutomirski CC: "H. Peter Anvin" , aarcange@redhat.com, ak@linux.intel.com, Stefani Seibold , x86@kernel.org, linux-kernel@vger.kernel.org, criu@openvz.org, mingo@redhat.com, john.stultz@linaro.org, tglx@linutronix.de Subject: Re: [CRIU] [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> <50CA6E4C.6000305@zytor.com> <50CA81A4.9040702@zytor.com> <50CA85BD.7070502@zytor.com> <8c3585bc-fc7d-4826-913c-f4581494d91d@email.android.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/14/2012 06:20 AM, Andy Lutomirski wrote: > On Thu, Dec 13, 2012 at 6:18 PM, H. Peter Anvin wrote: >> Wouldn't the vdso get mapped already and could be mremap()'d. If we > really need more control I'd almost push for a device/filesystem node > that could be mmapped the usual way. > > Hmm. That may work, but it'll still break ABI. I'm not sure that > criu is stable enough yet that we should care. Criu people? It's not yet, but we'd still appreciate the criu-friendly vdso redesign. > (In brief summary: how annoying would it be if the vdso was no longer > just a bunch of constant bytes that lived somewhere?) It depends on what vdso is going to be. In the perfect case it should a) be mremap-able to any address (or be at fixed address _forever_, but I assume this is not feasible); b) have entry points at fixed (or somehow movable) places. I admit that I didn't understand your question properly, if I did, please correct me. Thanks, Pavel