From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH] net: neighbour table ABI problem Date: Wed, 21 May 2008 13:35:10 -0700 (PDT) Message-ID: <20080521.133510.145260976.davem@davemloft.net> References: <20080521163815.GA5028@sc.homeunix.net> <4834544A.4010706@trash.net> <20080521104019.22f9c712@extreme> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: kaber@trash.net, tgraf@suug.ch, Stephane_Chazelas@yahoo.fr, netdev@vger.kernel.org To: shemminger@vyatta.com Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:39926 "EHLO sunset.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1758492AbYEUUfP (ORCPT ); Wed, 21 May 2008 16:35:15 -0400 In-Reply-To: <20080521104019.22f9c712@extreme> Sender: netdev-owner@vger.kernel.org List-ID: From: Stephen Hemminger Date: Wed, 21 May 2008 10:40:19 -0700 > The neighbor table time of last use information is returned in the incorrect > unit. Kernel to user space ABI's need to use USER_HZ (or milliseconds), otherwise > the application has to try and discover the real system HZ value which is problematic. > Linux has standardized on keeping USER_HZ consistent (100hz) even when kernel is > running internally at some other value. > > This change is small, but it breaks the ABI for older version of iproute2 utilities. > But these utilities are already broken since they are looking at the psched_hz values > which are completely different. So let's just go ahead and fix both kernel and user > space. Older utilities will just print wrong values. > > Signed-off-by: Stephen Hemminger In at least one sense the kernel has been providing a consistent value :-) I don't know what to do here, it's different from the other patch you posted today in that I can't see any easy way to not change behavior for old stuff. Can we add a new attribute or something like that?