From owner-freebsd-hackers@FreeBSD.ORG Wed Jun 9 13:26:28 2010 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 3524D1065674 for ; Wed, 9 Jun 2010 13:26:28 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from mail.zoral.com.ua (mx0.zoral.com.ua [91.193.166.200]) by mx1.freebsd.org (Postfix) with ESMTP id A35B78FC08 for ; Wed, 9 Jun 2010 13:26:27 +0000 (UTC) Received: from deviant.kiev.zoral.com.ua (root@deviant.kiev.zoral.com.ua [10.1.1.148]) by mail.zoral.com.ua (8.14.2/8.14.2) with ESMTP id o59DPvvx003539 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Wed, 9 Jun 2010 16:25:57 +0300 (EEST) (envelope-from kostikbel@gmail.com) Received: from deviant.kiev.zoral.com.ua (kostik@localhost [127.0.0.1]) by deviant.kiev.zoral.com.ua (8.14.4/8.14.4) with ESMTP id o59DPhU2035122; Wed, 9 Jun 2010 16:25:43 +0300 (EEST) (envelope-from kostikbel@gmail.com) Received: (from kostik@localhost) by deviant.kiev.zoral.com.ua (8.14.4/8.14.4/Submit) id o59DPhqo035121; Wed, 9 Jun 2010 16:25:43 +0300 (EEST) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: deviant.kiev.zoral.com.ua: kostik set sender to kostikbel@gmail.com using -f Date: Wed, 9 Jun 2010 16:25:43 +0300 From: Kostik Belousov To: jhell Message-ID: <20100609132543.GI83316@deviant.kiev.zoral.com.ua> References: <20100609121453.095d92b4@kibab.com> <4C0F9394.9030202@dataix.net> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="IoysBk3hhUmaUGAr" Content-Disposition: inline In-Reply-To: <4C0F9394.9030202@dataix.net> User-Agent: Mutt/1.4.2.3i X-Virus-Scanned: clamav-milter 0.95.2 at skuns.kiev.zoral.com.ua X-Virus-Status: Clean X-Spam-Status: No, score=-2.3 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_50, DNS_FROM_OPENWHOIS autolearn=no version=3.2.5 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on skuns.kiev.zoral.com.ua Cc: Ilya Bakulin , freebsd-hackers@freebsd.org Subject: Re: GSoC: registration of optional kernel features via sysctl: a question to the community X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 09 Jun 2010 13:26:28 -0000 --IoysBk3hhUmaUGAr Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jun 09, 2010 at 09:13:56AM -0400, jhell wrote: > On 06/09/2010 04:14, Ilya Bakulin wrote: > > Hi hackers! > >=20 > > While discussing my project's implementation details with my mentor, > > Alexander Leidinger, we've found that one of the ideas needs to be disc= ussed with community, > > to find out possible use cases. > > That is, if it should be possible to spoof non-existing features. For > > example, if currently running kernel doesn't support FreeBSD 5.0 compat > > layer, "kern.features.compat_freebsd5" will be absent when querying=20 > > features list. The question is -- are there any cases when we want > > "kern.features.compat_freebsd5" be present? If some feature is not in > > kernel, then presenting its existence to the userland is useless > > and may be even harmful, if, for example, some application relies on th= is feature. > > Or there are some scenarios where such cheat is useful? > >=20 >=20 > I can not think of any viable reason why one would want to "spoof" this > when it is not available. Many ports are doing wrong thing there, checking for run-time features at the build-time, turning on/off some functionality depending on its presence on the build host. --IoysBk3hhUmaUGAr Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (FreeBSD) iEYEARECAAYFAkwPllcACgkQC3+MBN1Mb4gU0gCg4T5LhRub/JYdxmgr5GpWOFrx 24QAnRvonnOInT6zfXqgFccAMyVCQYFb =K4nL -----END PGP SIGNATURE----- --IoysBk3hhUmaUGAr--