From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Thu, 28 Nov 2002 17:16:59 +0100 (MET) Received: from onda.linux-mips.net ([IPv6:::ffff:192.168.169.2]:16801 "EHLO dea.linux-mips.net") by ralf.linux-mips.org with ESMTP id ; Thu, 28 Nov 2002 17:16:48 +0100 Received: (from ralf@localhost) by dea.linux-mips.net (8.11.6/8.11.6) id gASGFJh18257; Thu, 28 Nov 2002 17:15:19 +0100 Date: Thu, 28 Nov 2002 17:15:19 +0100 From: Ralf Baechle To: "Maciej W. Rozycki" Cc: atul srivastava , linux-mips@linux-mips.org Subject: Re: a quick question regarding CONFIG_MIPS_UNCACHED.. Message-ID: <20021128171519.A18165@linux-mips.org> References: <20021127091114.27117.qmail@webmail24.rediffmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: ; from macro@ds2.pg.gda.pl on Thu, Nov 28, 2002 at 04:51:57PM +0100 Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 735 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: ralf@linux-mips.org Precedence: bulk X-list: linux-mips On Thu, Nov 28, 2002 at 04:51:57PM +0100, Maciej W. Rozycki wrote: > You are looking at obsolete code -- unless you have specific conditions > to use an explicit caching attribute for KSEG0, you should set it like the > rest of the code does it, i.e.: > > change_cp0_config(CONF_CM_CMASK, CONF_CM_DEFAULT); > > To avoid surprises here and elsewhere, you should make sure > CONFIG_NONCOHERENT_IO is set appropriately, too. We've talked about this before - the specification of the ll/sc instructions says they only work ok on cached memory. In the real world they seem to work also in uncached memory but I'd not bet the farm on that, too many implementations out there, too many chances for subtle bugs. Ralf