From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4BA11C433EF for ; Wed, 16 Mar 2022 07:25:40 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id BF1B110E6CC; Wed, 16 Mar 2022 07:25:39 +0000 (UTC) Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by gabe.freedesktop.org (Postfix) with ESMTPS id 2E15010E6CC for ; Wed, 16 Mar 2022 07:25:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1647415539; x=1678951539; h=message-id:date:mime-version:to:from:subject: content-transfer-encoding; bh=k8G+orSXKOqnwAq09iYZXX7BNJoCXyNB+We5mqzn1uo=; b=U+kPMeBX1yqeuePY3cauUzt0rVsTKPC9sjm5NLUKT758as0HbKuba7Qe p6KNiJHQ/MBjYf4vbpsVUceZoJlGD9vOJL8g2HIxCJaRL6LZJQgvNLyEb eUYBTn1VGhTesqz++aUaswOx+G15qc2DbwnGcF9ZahvNoLJT2/41LgaqV w5ktt7sy1u6vgnhmUXXsE2wAVtfGU91ZW8s9XQheve96JNxomSSHe0t7A X4l72FBJ9OueP4KO4o3dflVd4JfLFEZat3SJhkTxOD5Dq7XQuyYRNj3SB UINU7+x8qDQksZsU7IwL3gZbLs3wl4RMsFScnP2kOY01cU7MESRZzabJx A==; X-IronPort-AV: E=McAfee;i="6200,9189,10286"; a="342943289" X-IronPort-AV: E=Sophos;i="5.90,186,1643702400"; d="scan'208";a="342943289" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Mar 2022 00:25:36 -0700 X-IronPort-AV: E=Sophos;i="5.90,186,1643702400"; d="scan'208";a="557320546" Received: from sfhansen-mobl1.ger.corp.intel.com (HELO [10.249.254.132]) ([10.249.254.132]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Mar 2022 00:25:34 -0700 Message-ID: <162c1566-87c6-072f-d340-1693f6a71aea@linux.intel.com> Date: Wed, 16 Mar 2022 08:25:16 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.3.0 Content-Language: en-US To: Matthew Auld , Joonas Lahtinen , "Bloomfield, Jon" , Intel Graphics Development , Ramalingam C From: =?UTF-8?Q?Thomas_Hellstr=c3=b6m?= Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: [Intel-gfx] Small bar recovery vs compressed content on DG2 X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Hi! Do we somehow need to clarify in the headers the semantics for this? From my understanding when discussing the CCS migration series with Ram, the kernel will never do any resolving (compressing / decompressing) migrations or evictions which basically implies the following: *) Compressed data must have LMEM only placement, otherwise the GPU would read garbage if accessing from SMEM. *) Compressed data can't be assumed to be mappable by the CPU, because in order to ensure that on small BAR, the placement needs to be LMEM+SMEM. *) Neither can compressed data be part of a CAPTURE buffer, because that requires the data to be CPU-mappable. Are we (and user-mode drivers) OK with these restrictions, or do we need to rethink? Thanks, Thomas