Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262846AbVCJTQf (ORCPT ); Thu, 10 Mar 2005 14:16:35 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263038AbVCJTLm (ORCPT ); Thu, 10 Mar 2005 14:11:42 -0500 Received: from ylpvm15-ext.prodigy.net ([207.115.57.46]:38557 "EHLO ylpvm15.prodigy.net") by vger.kernel.org with ESMTP id S262998AbVCJS6Q (ORCPT ); Thu, 10 Mar 2005 13:58:16 -0500 Message-ID: <00b701c525a3$128c2ac0$6a004b0a@charlemagne> From: "Nate Edel" To: "Jason Luo" , "Arjan van de Ven" Cc: References: <20050310081634.GA29516@taniwha.stupidest.org> <1110445030.6291.57.camel@laptopd505.fenrus.org> Subject: Re: Can I get 200M contiguous physical memory? Date: Thu, 10 Mar 2005 10:57:54 -0800 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="Windows-1252"; reply-type=original Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2527 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2527 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1120 Lines: 26 From: "Arjan van de Ven" To: "Jason Luo" >> A data acquisition card. In DMA mode, the card need 200M contiguous >> memory for DMA. > > (or want to reserve memory at the boot commandline and then do really > really evil hacks) Such as booting the machine with "mem=(real memory - 200)M" and then just doing an ioremap of the top 200M of memory. It's not the most elegant way of doing things given that it requires user intervention at boot time, but I'm not sure it counts as a "really evil hack." Code-wise it's very simple - there's sample code in a couple of the in-RAM MTD(*) drivers you can use as a model. I'm not sure if this method will translate easily to non-x86 platforms if that's an issue. (* /drivers/mtd/devices/slram.c and /drivers/mtd/devices/mtdram.c ; I'm not sure which of these is more up to date.) - 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/