Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754011AbaA0R54 (ORCPT ); Mon, 27 Jan 2014 12:57:56 -0500 Received: from mail-ea0-f176.google.com ([209.85.215.176]:47303 "EHLO mail-ea0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753926AbaA0R5y (ORCPT ); Mon, 27 Jan 2014 12:57:54 -0500 Message-ID: <52E69E1E.3020202@monstr.eu> Date: Mon, 27 Jan 2014 18:57:50 +0100 From: Michal Simek Reply-To: monstr@monstr.eu User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130330 Thunderbird/17.0.5 MIME-Version: 1.0 To: Russell King - ARM Linux CC: Guennadi Liakhovetski , linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org, linux-mmc@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [Q] block / zynq: DMA bouncing References: <20140127170230.GQ15937@n2100.arm.linux.org.uk> <52E69B4E.5010604@monstr.eu> <20140127175231.GU15937@n2100.arm.linux.org.uk> In-Reply-To: <20140127175231.GU15937@n2100.arm.linux.org.uk> X-Enigmail-Version: 1.6 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="uFFiXq1NItkHisFCj743jDDeUTD4WRL1R" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --uFFiXq1NItkHisFCj743jDDeUTD4WRL1R Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 01/27/2014 06:52 PM, Russell King - ARM Linux wrote: > On Mon, Jan 27, 2014 at 06:45:50PM +0100, Michal Simek wrote: >> Why 0x4000? IRC Linux for ARM is using space for any purpose. >> Russell knows this much better than I. >=20 > Probably because as the kernel is loaded at 0x8000, it will place the > swapper page table at 0x4000, thus covering from 0x4000 upwards. Ah yeah swapper. >=20 > Thus, the majority of your un-DMA-able memory will be kernel text or > swapper page tables. Yes, exactly. 0x0 - 0x4000 - reserving not to be used by DMA 0x4000 - 0x8000 swapper page table 0x8000 - 0x80000 kernel text + up Thanks, Michal --=20 Michal Simek, Ing. (M.Eng), OpenPGP -> KeyID: FE3D1F91 w: www.monstr.eu p: +42-0-721842854 Maintainer of Linux kernel - Microblaze cpu - http://www.monstr.eu/fdt/ Maintainer of Linux kernel - Xilinx Zynq ARM architecture Microblaze U-BOOT custodian and responsible for u-boot arm zynq platform --uFFiXq1NItkHisFCj743jDDeUTD4WRL1R Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iEYEARECAAYFAlLmnh8ACgkQykllyylKDCHf0gCeLPB3O2+U+u37SyE1sIAVO4np WpkAn1VPgiAYBbDuJClZRZKL901DDQ15 =MZGi -----END PGP SIGNATURE----- --uFFiXq1NItkHisFCj743jDDeUTD4WRL1R-- -- 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/