Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262237AbVDFP4o (ORCPT ); Wed, 6 Apr 2005 11:56:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262238AbVDFP4n (ORCPT ); Wed, 6 Apr 2005 11:56:43 -0400 Received: from cam-admin0.cambridge.arm.com ([193.131.176.58]:64724 "EHLO cam-admin0.cambridge.arm.com") by vger.kernel.org with ESMTP id S262237AbVDFP4g (ORCPT ); Wed, 6 Apr 2005 11:56:36 -0400 To: Bas Vermeulen Cc: linux-kernel@vger.kernel.org Subject: Re: NOMMU - How to reserve 1 MB in top of memory in a clean way References: <1112781027.2687.6.camel@laptop.blackstar.nl> <1112800564.2687.40.camel@laptop.blackstar.nl> From: Catalin Marinas Date: Wed, 06 Apr 2005 16:56:34 +0100 In-Reply-To: <1112800564.2687.40.camel@laptop.blackstar.nl> (Bas Vermeulen's message of "Wed, 06 Apr 2005 17:16:04 +0200") Message-ID: User-Agent: Gnus/5.1007 (Gnus v5.10.7) Emacs/21.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1296 Lines: 30 Bas Vermeulen wrote: > This will put me in the zone of 'it ain't ever going to be integrated'. > I'd preferrably find a solution without changing the zones. My ideal > solution would be grabbing pages before they are assigned to a zone, or > at least for the zone to recognize them as used. The order of the zones was initially chosen based on x86 and ISA bus. This is no longer valid for all the platforms (for example, the 1st MB can be SSRAM and not usable for DMA). This might be possible but I've never tried (and not sure how it would work with nommu) - define CONFIG_NUMA and use 2 memory banks, one from 0 to max - 1M and the 2nd being 1MB. You can define the zone sizes for each node when calling free_area_init_node() so that the first node doesn't have any DMA area and the 2nd one has only DMA. Maybe other could comment on this, not sure it will work. What core are you using? A third option could be to define your own dma_alloc* functions and not give the top MB to the kernel (mem=...). -- Catalin - 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/