Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 10 Oct 2002 18:47:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 10 Oct 2002 18:47:00 -0400 Received: from mailout05.sul.t-online.com ([194.25.134.82]:2495 "EHLO mailout05.sul.t-online.com") by vger.kernel.org with ESMTP id ; Thu, 10 Oct 2002 18:46:55 -0400 Date: Fri, 11 Oct 2002 00:52:21 +0200 From: Martin Waitz To: "H. Peter Anvin" Cc: linux-kernel@vger.kernel.org Subject: weird semantics of cpu/*/msr Message-ID: <20021010225221.GA1552@admingilde.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="k+w/mQv8wyuph6w0" Content-Disposition: inline User-Agent: Mutt/1.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1934 Lines: 60 --k+w/mQv8wyuph6w0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable hi :) the i386 msr driver is a bit strange: * when reading/writing, it does not update the file position/msr register * file position is used directly as msr register that is, reads with count>8 do read from the same register multiple times, and writes overwrite themselves. i would expect the following semantics: * file position is (msr register * 8). position%8!=3D0 is invalid * read/write updating file position. that would make it possible to write/read multiple MSRs with one syscall, which is very handy when initializing P4 performance counters. should i implement that behaviour? of course it would break binary compatibility with existing uses of that drivers. perhaps we would need a new location for the new api. comments? --=20 CU, / Friedrich-Alexander University Erlangen, Germany Martin Waitz // [Tali on IRCnet] [tali.home.pages.de] _________ ______________/// - - - - - - - - - - - - - - - - - - - - /// dies ist eine manuell generierte mail, sie beinhaltet // tippfehler und ist auch ohne grossbuchstaben gueltig. / - Wer bereit ist, grundlegende Freiheiten aufzugeben, um sich=20 kurzfristige Sicherheit zu verschaffen, der hat weder Freiheit=20 noch Sicherheit verdient. Benjamin Franklin (1706 - 1790) --k+w/mQv8wyuph6w0 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.0 (GNU/Linux) iD8DBQE9pgSkj/Eaxd/oD7IRAk2GAJ0UoEGq8XH7d7Bo9bvemoXc8WLF+QCeMKVO LFyItz+7lBE8D2D0bmSVczE= =Ucsa -----END PGP SIGNATURE----- --k+w/mQv8wyuph6w0-- - 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/