Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754771AbaJUIOH (ORCPT ); Tue, 21 Oct 2014 04:14:07 -0400 Received: from mail-wg0-f49.google.com ([74.125.82.49]:41774 "EHLO mail-wg0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754662AbaJUIOB (ORCPT ); Tue, 21 Oct 2014 04:14:01 -0400 Date: Tue, 21 Oct 2014 10:13:55 +0200 From: Richard Cochran To: Thomas Shao Cc: Thomas Gleixner , "gregkh@linuxfoundation.org" , LKML , "devel@linuxdriverproject.org" , "olaf@aepfle.de" , "apw@canonical.com" , "jasowang@redhat.com" , KY Srinivasan , John Stultz , Richard Cochran Subject: Re: [PATCH v2 1/2] timekeeping: add EXPORT_SYMBOL_GPL for do_adjtimex() Message-ID: <20141021081355.GA6808@netboy> References: <1413362372-16236-1-git-send-email-huishao@microsoft.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 21, 2014 at 03:18:58AM +0000, Thomas Shao wrote: > > In some situation, the user is not able to enable guest VM to sync with external > time source, like NTP. But the host is still synced with a trusted time source. But the guest *is* networked, right? (Otherwise syncing the guest's clock is pointless.) > I've got some feedbacks from Richard and Mike, including reference NTP implementation > and do the adjustment in the host side. I've already referenced some NTP design in > my patch. I would consider my patch as a simplified implementation. I really don't think we want a half baked servo in some random driver. Instead, why not present the time difference using a standard interface? > I've also considered > the host side implementation. But in host, we can only set time but not gradually slew/adjust > time, Why not implement adjustment in the host? > which is not acceptable for the time sync solution.We still recommend user to configure > NTP on the guest, which provides better accuracy. But if NTP is not applicable, this could be > another option. You did not really answer any of my objections, nor did you consider the alternative ideas which I offered. Would you care to address those? Thanks, Richard -- 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/