From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id E45BBB70A3 for ; Fri, 10 Sep 2010 23:37:51 +1000 (EST) Subject: Re: how to understand powerpc's BRx ORx Mime-Version: 1.0 (Apple Message framework v1081) Content-Type: text/plain; charset=us-ascii From: Kumar Gala In-Reply-To: <201009101356067140460@gmail.com> Date: Fri, 10 Sep 2010 08:37:42 -0500 Message-Id: References: <201009101356067140460@gmail.com> To: hacklu Cc: linuxppc-dev List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Sep 10, 2010, at 12:56 AM, hacklu wrote: > I didn't understand the address mask. > it's said that: BR[BA] is the base address,the OR[AM] is the address = mask, > "Provides masking for corresponding BRx bits. By masking address=20 > bits independently, SDRAM devices of different size address ranges can = be used. Clearing=20 > bits masks the corresponding address bit. Setting bits causes the = corresponding address=20 > bit to be compared with the address pins. Address mask bits can be set = or cleared in any=20 > order, allowing a resource to reside in more than one area of the = address map. SDAM can=20 > be read or written at any time." >=20 > how to understand it? > for instance, if my BR0[BA]=3D0111_0000_0000_0000_0, = OR0[AM]=3D1111_1111_1111 > if I want to access the 0x70000000 or the 0x71000001.what address = calculate will be taken? Can you let us know which chip you are looking at using? There is a bit = of variation so its useful to know. - k=