From owner-svn-src-head@FreeBSD.ORG Tue Jan 8 03:00:33 2013 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by hub.freebsd.org (Postfix) with ESMTP id CFEC2EDC; Tue, 8 Jan 2013 03:00:33 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from kib.kiev.ua (kib.kiev.ua [IPv6:2001:470:d5e7:1::1]) by mx1.freebsd.org (Postfix) with ESMTP id 45C156EE; Tue, 8 Jan 2013 03:00:33 +0000 (UTC) Received: from tom.home (kostik@localhost [127.0.0.1]) by kib.kiev.ua (8.14.5/8.14.5) with ESMTP id r0830M6G028151; Tue, 8 Jan 2013 05:00:22 +0200 (EET) (envelope-from kostikbel@gmail.com) DKIM-Filter: OpenDKIM Filter v2.7.4 kib.kiev.ua r0830M6G028151 Received: (from kostik@localhost) by tom.home (8.14.5/8.14.5/Submit) id r0830Mpt028150; Tue, 8 Jan 2013 05:00:22 +0200 (EET) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: tom.home: kostik set sender to kostikbel@gmail.com using -f Date: Tue, 8 Jan 2013 05:00:22 +0200 From: Konstantin Belousov To: Oleksandr Tymoshenko Subject: Re: svn commit: r245147 - head/sys/arm/include Message-ID: <20130108030022.GC82219@kib.kiev.ua> References: <201301080240.r082eKVq080302@svn.freebsd.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="+plSmdOTvOCX/8Oy" Content-Disposition: inline In-Reply-To: <201301080240.r082eKVq080302@svn.freebsd.org> User-Agent: Mutt/1.5.21 (2010-09-15) X-Spam-Status: No, score=-2.0 required=5.0 tests=ALL_TRUSTED,BAYES_00, DKIM_ADSP_CUSTOM_MED,FREEMAIL_FROM,NML_ADSP_CUSTOM_MED autolearn=no version=3.3.2 X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on tom.home Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 08 Jan 2013 03:00:33 -0000 --+plSmdOTvOCX/8Oy Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Jan 08, 2013 at 02:40:20AM +0000, Oleksandr Tymoshenko wrote: > Author: gonzo > Date: Tue Jan 8 02:40:20 2013 > New Revision: 245147 > URL: http://svnweb.freebsd.org/changeset/base/245147 >=20 > Log: > Switch default cache type for ARMv6/ARMv7 from write-through to > writeback-writeallocate Could you, please, describe how this is supposed to work. Assume that a process mapped the same file page at two different addresses, both read-write, and writes to both mappings. Usermode code does not consider the need to flush caches or synchronize writes into non-overlapping regions, usually. Would it break, i.e. could the values appear in the page which were never written to it ? Another similar question, sf buffers on ARM flush the cache on sf_buf_free() (sometimes). If the page, for which the sf buffer is created, mapped into the userspace read-write, could it be that a value appears that was never written ? Note that sf buffers are used e.g. by uiomove_fromphys(). --+plSmdOTvOCX/8Oy Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (FreeBSD) iQIcBAEBAgAGBQJQ64vFAAoJEJDCuSvBvK1BfEwP/A4xXCfW82HgQHNeT5mxlRp6 /Gw2UD7T7c6+3/1cQUDN10hrlv52hVI8et30Q0S5/2rjB3YeQ/SROHwzXRNCtOgI JM/sAw3LS6ksXvMGzqsUK53676G/Oso4C+bYLUJELkIihhXxDvpscbI7O2s1VLBZ fMjSuiMpMhHypV2+Y48RP5EdsDXbVNkloMvifHEcBaN+HePK4qkQHZgnAyDoz3+E YC+FOdORExzSYUyuBYXEWLEMtNBkHKJhMaGIXaqzCnuyO2bvY5uW91MQu+rk/iCy DpC3cnIcFlnRX6WdZQoOHoVJDXl9jYaQynMZTDfbM9s1qTbUd5H+wjb+LXcw8C4Y j6ovmaL8CnEU/i7VcWlodwib/ZoCiBv5hjFILi3A08kfUKtiM8iijEyVe8YUALR2 AbkRRpM6Ce8Obu+T+/BXO9VX7UQC5ayyqmHSBE8NI4HlBjKAWguR+53WjmxDhbf7 R+Mquegi8zVEZ7/gnwdv1sleukheb3QfJAXE6WGWEfxEtSj7sqCC8UozBupIKRe7 zVUzkKpdcNCcvUi6hiYYGH2XUMzfa9cyY2yFIRAF9HCiHn2/zQC2wLQ1ZqcPwqur LHQwf02mbRz87k+P0V61FxkJhUrUFe6s36GlyeoPO4V6t5ImTzFOsGpI9p/VWKXL 4n+lb/EuD0RfkpdKnKyk =f1Yd -----END PGP SIGNATURE----- --+plSmdOTvOCX/8Oy--