From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from NAM03-CO1-obe.outbound.protection.outlook.com (mail-co1nam03on0723.outbound.protection.outlook.com [IPv6:2a01:111:f400:fe48::723]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id E12D41A1E59 for ; Thu, 8 Sep 2016 10:33:56 -0700 (PDT) Received: from AT5PR84MB0291.NAMPRD84.PROD.OUTLOOK.COM (10.162.138.25) by AT5PR84MB0291.NAMPRD84.PROD.OUTLOOK.COM (10.162.138.25) with Microsoft SMTP Server (version=TLS1_0, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA_P384) id 15.1.609.9; Thu, 8 Sep 2016 17:33:55 +0000 Received: from AT5PR84MB0291.NAMPRD84.PROD.OUTLOOK.COM ([10.162.138.25]) by AT5PR84MB0291.NAMPRD84.PROD.OUTLOOK.COM ([10.162.138.25]) with mapi id 15.01.0609.016; Thu, 8 Sep 2016 17:33:55 +0000 From: "Cohen, Eugene" To: Ard Biesheuvel , "edk2-devel@lists.01.org" , "leif.lindholm@linaro.org" Thread-Topic: [edk2] [PATCH] ArmPlatformPkg: remove EFI_MEMORY_UC attribute from normal memory Thread-Index: AQHSCaj6ofgkiUkAD0afsTC+p9D196Bv2MvA Date: Thu, 8 Sep 2016 17:33:55 +0000 Message-ID: References: <1473322418-9158-1-git-send-email-ard.biesheuvel@linaro.org> In-Reply-To: <1473322418-9158-1-git-send-email-ard.biesheuvel@linaro.org> Accept-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: spf=none (sender IP is ) smtp.mailfrom=eugene@hp.com; 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received-spf: None (protection.outlook.com: hp.com does not designate permitted sender hosts) spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM MIME-Version: 1.0 X-OriginatorOrg: hp.com X-MS-Exchange-CrossTenant-originalarrivaltime: 08 Sep 2016 17:33:55.5918 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: ca7981a2-785a-463d-b82a-3db87dfc3ce6 X-MS-Exchange-Transport-CrossTenantHeadersStamped: AT5PR84MB0291 Subject: Re: [PATCH] ArmPlatformPkg: remove EFI_MEMORY_UC attribute from normal memory X-BeenThere: edk2-devel@lists.01.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: EDK II Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 08 Sep 2016 17:33:57 -0000 Content-Language: en-US Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable Ard, > So remove the EFI_MEMORY_UC attribute that we set by default on > system RAM. > If any region requires this attribute, it is up to the driver to set this > attribute, and to ensure that no offending operations are performed > on it. > For DMA common-buffer operations on systems without snooping DMA capabiliti= es, UC or WC mapping of system memory regions is required. > EFI_RESOURCE_ATTRIBUTE_PRESENT | > EFI_RESOURCE_ATTRIBUTE_INITIALIZED | > - EFI_RESOURCE_ATTRIBUTE_UNCACHEABLE | > EFI_RESOURCE_ATTRIBUTE_WRITE_COMBINEABLE | > EFI_RESOURCE_ATTRIBUTE_WRITE_THROUGH_CACHEABLE | > EFI_RESOURCE_ATTRIBUTE_WRITE_BACK_CACHEABLE | The EFI_RESOURCE_ATTRIBUTE_UNCACHEABLE bit your removing is removing the ca= pability for uncacheable memory such that even if a driver wanted to make a= DMA buffer uncacheable GCD will no longer allow this because the resource = does not support this capability. Is it your intent to indicate that system memory is no longer capable of be= ing uncacheable? If so how would you plan to accomodate the DMA use case f= or GCD SetMemorySpaceAttributes? Thanks, Eugene