Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758941Ab2BJKQB (ORCPT ); Fri, 10 Feb 2012 05:16:01 -0500 Received: from mail-bk0-f46.google.com ([209.85.214.46]:45110 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754173Ab2BJKQA (ORCPT ); Fri, 10 Feb 2012 05:16:00 -0500 Message-ID: <4F34EE5C.7040103@monstr.eu> Date: Fri, 10 Feb 2012 11:15:56 +0100 From: Michal Simek Reply-To: monstr@monstr.eu User-Agent: Thunderbird 2.0.0.22 (X11/20090625) MIME-Version: 1.0 To: Russell King - ARM Linux CC: Marek Szyprowski , Kyungmin Park , Ohad Ben-Cohen , LKML , linux-arm-kernel@lists.arm.linux.org.uk Subject: Re: CMA on arm from zero address References: <4F326A4E.1030106@monstr.eu> <20120208130807.GJ889@n2100.arm.linux.org.uk> <4F3276D6.3060507@monstr.eu> <20120208132622.GL889@n2100.arm.linux.org.uk> In-Reply-To: <20120208132622.GL889@n2100.arm.linux.org.uk> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1256 Lines: 37 Russell King - ARM Linux wrote: > On Wed, Feb 08, 2012 at 02:21:26PM +0100, Michal Simek wrote: >> First of all I have found how to do it (by CONFIG_PHYS_OFFSET) so the >> problem is in QEMU. > > So you're basically not telling the kernel about the first 32MB of memory. It is not a problem. > >> Currently experimenting how to convince CMA to allocate that memory for >> my purpose. > > Which means it won't be part of the kernels normal memory map, and so > won't be in the page pool. So CMA won't be able to help. > > Instead, just ignore the first 32MB of RAM, and map it like any other > peripheral to gain access to it. You might need to use ioremap_wc() > to avoid treating the memory as a 'device type' in ARMv6+. I switched from cma to dma_declare_coherent_memory which does exactly what I wanted to do. Thanks, Michal -- Michal Simek, Ing. (M.Eng) w: www.monstr.eu p: +42-0-721842854 Maintainer of Linux kernel 2.6 Microblaze Linux - http://www.monstr.eu/fdt/ Microblaze U-BOOT custodian -- 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/