From owner-freebsd-arch@FreeBSD.ORG Thu Sep 2 00:06:16 2004 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 303DF16A4CE; Thu, 2 Sep 2004 00:06:16 +0000 (GMT) Received: from odin.ac.hmc.edu (Odin.AC.HMC.Edu [134.173.32.75]) by mx1.FreeBSD.org (Postfix) with ESMTP id 10FBE43D49; Thu, 2 Sep 2004 00:06:16 +0000 (GMT) (envelope-from brdavis@odin.ac.hmc.edu) Received: from odin.ac.hmc.edu (localhost.localdomain [127.0.0.1]) by odin.ac.hmc.edu (8.13.0/8.13.0) with ESMTP id i8206cWU012231; Wed, 1 Sep 2004 17:06:38 -0700 Received: (from brdavis@localhost) by odin.ac.hmc.edu (8.13.0/8.13.0/Submit) id i8206bFZ012230; Wed, 1 Sep 2004 17:06:37 -0700 Date: Wed, 1 Sep 2004 17:06:37 -0700 From: Brooks Davis To: Julian Elischer Message-ID: <20040902000637.GA4120@odin.ac.hmc.edu> References: <20040901193445.GC12483@odin.ac.hmc.edu> <41364415.9040708@elischer.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="qDbXVdCdHGoSgWSk" Content-Disposition: inline In-Reply-To: <41364415.9040708@elischer.org> User-Agent: Mutt/1.4.1i X-Virus-Scanned: by amavisd-new X-Spam-Status: No, hits=0.0 required=8.0 tests=none autolearn=no version=2.63 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on odin.ac.hmc.edu cc: arch@freebsd.org cc: scottl@freebsd.org cc: julian@freebsd.FreeBSD.ORG Subject: Re: if_data size issues X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 02 Sep 2004 00:06:16 -0000 --qDbXVdCdHGoSgWSk Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Sep 01, 2004 at 02:50:13PM -0700, Julian Elischer wrote: >=20 >=20 > Brooks Davis wrote: >=20 > >My recent commit to net/if.h adding ifi_epoch to struct if_data had > >unintended consequences. Specifically, because of the way ifconfig > >uses RTM_IFINFO routing socket messages via sysctl to obtain interface > >information, the value of sizeof(struct if_data) must be the same in the > >kernel and userland. I have committed a fix from Peter which allows > >ifconfig to handle growth of struct if_data. Unfortunately, this does > >not fix old ifconfigs with new kernels. >=20 > What is the reason that ifi_epoch needs to be accurate the microsecond? > you have a u)long just next door that is unused that could hold a=20 > seconds count that would last > at least 68 years if expressed as a count from boot time. I dug into the RFCs and found that ifCounterDiscontinuityTime is of type TimeStamp which is a TimeTick with the epoch of sysUpTime. The resolution of a TimeTick is 1/100s. Thus, given our choice of counters, struct timeval is most appropriate. However, in this case, meeting the letter of the rule is arguably unnecessary. Given the pain this change is causing and the limited impact of reducing the precision of ifi_epoch, I propose the following: - Back out the ifi_epoch addition. - MT5 and MT4 Peter's size change. - Turn ifi_unused into ifi_epoch. - After 5.3 is released, declare that upgrades to 6.0 from releases other then 4.x (x>=3D11) and 5.y (y>=3D3) require special handling and allow if_data to grow as demand requires. - If additional precision is deemed necessary at some future date, add a second ifi_epoch_tv. -- Brooks --=20 Any statement of the form "X is the one, true Y" is FALSE. PGP fingerprint 655D 519C 26A7 82E7 2529 9BF0 5D8E 8BE9 F238 1AD4 --qDbXVdCdHGoSgWSk Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.1 (GNU/Linux) iD8DBQFBNmQMXY6L6fI4GtQRAn+sAJ9Jss/JgMyDzv651JUdtCWKSVHvdwCeK5eA 9PDn4A7pkl8jKzkRmoBaLQo= =M5BZ -----END PGP SIGNATURE----- --qDbXVdCdHGoSgWSk--